algs4 | Algorithms, 4th edition textbook code and libraries | Learning library

by kevin-wayne Java Version: Current License: GPL-3.0

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kandi X-RAY | algs4 Summary

algs4 is a Java library typically used in Institutions, Learning, Education, Tutorial, Learning, Example Codes applications. algs4 has no bugs, it has no vulnerabilities, it has build file available, it has a Strong Copyleft License and it has medium support. You can download it from GitHub.

Algorithms, 4th edition textbook code and libraries

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kandi-support Support

algs4 has a medium active ecosystem.
It has 6721 star(s) with 2506 fork(s). There are 403 watchers for this library.
It had no major release in the last 12 months.
There are 11 open issues and 44 have been closed. On average issues are closed in 104 days. There are 3 open pull requests and 0 closed requests.
It has a neutral sentiment in the developer community.
The latest version of algs4 is current.

algs4 Support

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algs4 Support

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quality kandi Quality

algs4 has 0 bugs and 0 code smells.

algs4 Quality

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algs4 Quality

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security Security

algs4 has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
algs4 code analysis shows 0 unresolved vulnerabilities.
There are 0 security hotspots that need review.

algs4 Security

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algs4 Security

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license License

algs4 is licensed under the GPL-3.0 License. This license is Strong Copyleft.
Strong Copyleft licenses enforce sharing, and you can use them when creating open source projects.

algs4 License

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algs4 License

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build Reuse

algs4 releases are not available. You will need to build from source code and install.
Build file is available. You can build the component from source.
Installation instructions are available. Examples and code snippets are not available.

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algs4 Reuse

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Top functions reviewed by kandi - BETA

kandi has reviewed algs4 and discovered the below as its top functions. This is intended to give you an instant insight into algs4 implemented functionality, and help decide if they suit your requirements.

Simulates the simulation with the specified number of particles .
Splits this node into two trees .
Sets the segments .
Creates a digraph with a strong component c .
Returns a double array from the specified filename .
Ensures that a solution is valid .
Checks that all the edges are consistent .
Finds the closest pair of points in the given array .
Saves offscreen image .
Augments the residual

algs4 Key Features

Our original goal was to cover the 50 algorithms that every programmer should know. We use the word programmer to refer to anyone engaged in trying to accomplish something with the help of a computer, including scientists, engineers, and applications developers, not to mention college students in science, engineering, and computer science. The code is optimized for clarity, portability, and efficiency. While some of our implementations are as fast as (or faster than) their counterparts in java.util, our main goal is to express the core algorithmic ideas in an elegant and simple manner. While we embrace some advanced Java features (such as generics and iterators), we avoid those that interfere with the exposition (such as inheritance and concurrency).

algs4 Examples and Code Snippets

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Java Cannot Load Main Class Without Adding .java

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$ java -cp ".lift/algs4.jar;." RandomWord < coin.txt

$ java -cp ".lift/algs4.jar:." RandomWord < coin.txt

-----------------------

$ java -cp ".lift/algs4.jar;." RandomWord < coin.txt

$ java -cp ".lift/algs4.jar:." RandomWord < coin.txt

compareTo with objects returns a false while it is true

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public class MyBST {  

   private Object e;
  
   public MyBST(Object e) {
        this.e = e;
    }

    public Object getE(){
        return e;
    }
    
    @Override
    public int hashCode() {
        return Objects.hashCode(e);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (!(obj instanceof MyBST))
            return false;
        MyBST me = (MyBST) obj;
        if (e == null) {
            if (me.e != null)
                return false;
        } else if (!e.equals(me.e))
            return false;
        return true;
    }
}

class MyBST<T extends Comparable<? super T>> implements Comparable<MyBST<T>>{

    private T e;

    public MyBST(T e){
        this.e = e;
    }

    public T getE(){
        return e;
    }
    
    @Override
    public int compareTo(MyBST<T> o) {
        return e.compareTo(o.e);    
    }
}

class Apple {
    String type;
    int weight;
}

class MyBST implements Comparable<MyBST> {
    
    private Apple apple;
    
    public MyBST(Apple apple) {
        this.apple = apple;
    }
    
    @Override
    public int compareTo(MyBST e) {
        // this could be different depending on how you wanted
        // to compare one apple to another. This comparison favors
        // type over weight.

        // check type - String class implements comparable
        int ret = apple.type.compareTo(e.apple.type);
        if (ret != 0) { 
            return ret;
        }
        
        // same type so check weight
        if (apple.weight < e.apple.weight) {
            return -1;
        }
        if (apple.weight > e.apple.weight) {
            return 1;
        }
        return 0;  // equals apples based on criteria
    }
}

    private Object getE(){
        return e;
    }

-----------------------


public class MyBST {  

   private Object e;
  
   public MyBST(Object e) {
        this.e = e;
    }

    public Object getE(){
        return e;
    }
    
    @Override
    public int hashCode() {
        return Objects.hashCode(e);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (!(obj instanceof MyBST))
            return false;
        MyBST me = (MyBST) obj;
        if (e == null) {
            if (me.e != null)
                return false;
        } else if (!e.equals(me.e))
            return false;
        return true;
    }
}

class MyBST<T extends Comparable<? super T>> implements Comparable<MyBST<T>>{

    private T e;

    public MyBST(T e){
        this.e = e;
    }

    public T getE(){
        return e;
    }
    
    @Override
    public int compareTo(MyBST<T> o) {
        return e.compareTo(o.e);    
    }
}

class Apple {
    String type;
    int weight;
}

class MyBST implements Comparable<MyBST> {
    
    private Apple apple;
    
    public MyBST(Apple apple) {
        this.apple = apple;
    }
    
    @Override
    public int compareTo(MyBST e) {
        // this could be different depending on how you wanted
        // to compare one apple to another. This comparison favors
        // type over weight.

        // check type - String class implements comparable
        int ret = apple.type.compareTo(e.apple.type);
        if (ret != 0) { 
            return ret;
        }
        
        // same type so check weight
        if (apple.weight < e.apple.weight) {
            return -1;
        }
        if (apple.weight > e.apple.weight) {
            return 1;
        }
        return 0;  // equals apples based on criteria
    }
}

    private Object getE(){
        return e;
    }

-----------------------


public class MyBST {  

   private Object e;
  
   public MyBST(Object e) {
        this.e = e;
    }

    public Object getE(){
        return e;
    }
    
    @Override
    public int hashCode() {
        return Objects.hashCode(e);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (!(obj instanceof MyBST))
            return false;
        MyBST me = (MyBST) obj;
        if (e == null) {
            if (me.e != null)
                return false;
        } else if (!e.equals(me.e))
            return false;
        return true;
    }
}

class MyBST<T extends Comparable<? super T>> implements Comparable<MyBST<T>>{

    private T e;

    public MyBST(T e){
        this.e = e;
    }

    public T getE(){
        return e;
    }
    
    @Override
    public int compareTo(MyBST<T> o) {
        return e.compareTo(o.e);    
    }
}

class Apple {
    String type;
    int weight;
}

class MyBST implements Comparable<MyBST> {
    
    private Apple apple;
    
    public MyBST(Apple apple) {
        this.apple = apple;
    }
    
    @Override
    public int compareTo(MyBST e) {
        // this could be different depending on how you wanted
        // to compare one apple to another. This comparison favors
        // type over weight.

        // check type - String class implements comparable
        int ret = apple.type.compareTo(e.apple.type);
        if (ret != 0) { 
            return ret;
        }
        
        // same type so check weight
        if (apple.weight < e.apple.weight) {
            return -1;
        }
        if (apple.weight > e.apple.weight) {
            return 1;
        }
        return 0;  // equals apples based on criteria
    }
}

    private Object getE(){
        return e;
    }

-----------------------


public class MyBST {  

   private Object e;
  
   public MyBST(Object e) {
        this.e = e;
    }

    public Object getE(){
        return e;
    }
    
    @Override
    public int hashCode() {
        return Objects.hashCode(e);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (!(obj instanceof MyBST))
            return false;
        MyBST me = (MyBST) obj;
        if (e == null) {
            if (me.e != null)
                return false;
        } else if (!e.equals(me.e))
            return false;
        return true;
    }
}

class MyBST<T extends Comparable<? super T>> implements Comparable<MyBST<T>>{

    private T e;

    public MyBST(T e){
        this.e = e;
    }

    public T getE(){
        return e;
    }
    
    @Override
    public int compareTo(MyBST<T> o) {
        return e.compareTo(o.e);    
    }
}

class Apple {
    String type;
    int weight;
}

class MyBST implements Comparable<MyBST> {
    
    private Apple apple;
    
    public MyBST(Apple apple) {
        this.apple = apple;
    }
    
    @Override
    public int compareTo(MyBST e) {
        // this could be different depending on how you wanted
        // to compare one apple to another. This comparison favors
        // type over weight.

        // check type - String class implements comparable
        int ret = apple.type.compareTo(e.apple.type);
        if (ret != 0) { 
            return ret;
        }
        
        // same type so check weight
        if (apple.weight < e.apple.weight) {
            return -1;
        }
        if (apple.weight > e.apple.weight) {
            return 1;
        }
        return 0;  // equals apples based on criteria
    }
}

    private Object getE(){
        return e;
    }

How to save permutation in a Set Java

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...
        for (int i = 0; i < tes.toArray().length; i++) {
            Integer key = it.next();
            bst1.put(key, 0);
        }
        Set<Stack<Integer>> combos = combos(tes, stack, tes.size()); //there you have set with all Stacks
    }
}

    public static Set<Stack<Integer>> combos(Set<Integer> items, Stack<Integer> stack, int size) {
    Set<Stack<Integer>> set = new HashSet<>();

    if(stack.size() == size) {
        System.out.println(stack.to);
        set.add((Stack) stack.clone());
    }

    Integer[] itemz = items.toArray(new Integer[0]);
    for(Integer i : itemz) {
        stack.push(i);
        items.remove(i);
        set.addAll(combos(items, stack, size));
        items.add(stack.pop());
    }
    return set;
}

How to show top to bottom leaks in my path

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public class AssignmentTwo {
    public static void main(String[] args) {
        int n      = 500;
        double p   = 0.60;

        StdDraw.enableDoubleBuffering();
        boolean[][] open = Percolation.random(n, p);
        StdDraw.clear();
        StdDraw.setPenColor(StdDraw.PINK);
        Percolation.show(open, false);
        StdDraw.setPenColor(StdDraw.BLACK);
        StdDraw.show();
        StdDraw.disableDoubleBuffering();
         boolean[][] full = Percolation.flow(open);
         Percolation.show(full, true);
    }
}

How to count number of edges between red and white nodes in a graph?

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    private int countEdges(Graph G, int[] rednodes) {
        int count = 0;
        Arrays.sort(rednodes);
        for ( int rednode : rednodes ) {
            for ( int adj : G.adj(rednode) ) {
                if ( Arrays.binarySearch(rednodes, adj) < 0 ) {
                    count++;
                }
            }
            
        }
        return count;
    }

How to use read file from URI using C# in PowerShell line by line?

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# Set $f to point to the target file on the web
$f = 'https://algs4.cs.princeton.edu/15uf/tinyUF.txt'

# $wc to represent the WebClient
$wc = [System.Net.WebClient]::new()

# Create a stream object, using the .OpenRead method on $f
$stream = $wc.OpenRead($f)

# Create a reader of the stream using System.IO.StreamReader
$reader = [System.IO.StreamReader]($stream)

# ForEach-Object didn't play nice, so using while until it displays the last line of the file
while (-not($reader.EndOfStream)) {
    $line = $reader.ReadLine();
    $line
}

# Close the StreamReader
$reader.Close()

# Dispose of the WebClient
$wc.Dispose()

Ruby Heapsort: `sink': undefined method `>' for nil:NilClass

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if !a[j + 1].nil? # check if there is a right child

 while n > 1
    swap(a, 1, n)
    n -= 1
    sink(a, 1, n)
 end

  def sink(a, k, n)
    while 2 * k <= n
      j = 2 * k # child

      if j + 1 <= n # check if there is a right child
        j += 1 if j > 1 && less(a, j, j + 1) # if left child less than right child
      end

      break if !less(a, k, j) # If parent greater than child break
      swap(a, k, j)
      k = j
    end
  end

-----------------------

if !a[j + 1].nil? # check if there is a right child

 while n > 1
    swap(a, 1, n)
    n -= 1
    sink(a, 1, n)
 end

  def sink(a, k, n)
    while 2 * k <= n
      j = 2 * k # child

      if j + 1 <= n # check if there is a right child
        j += 1 if j > 1 && less(a, j, j + 1) # if left child less than right child
      end

      break if !less(a, k, j) # If parent greater than child break
      swap(a, k, j)
      k = j
    end
  end

-----------------------

if !a[j + 1].nil? # check if there is a right child

 while n > 1
    swap(a, 1, n)
    n -= 1
    sink(a, 1, n)
 end

  def sink(a, k, n)
    while 2 * k <= n
      j = 2 * k # child

      if j + 1 <= n # check if there is a right child
        j += 1 if j > 1 && less(a, j, j + 1) # if left child less than right child
      end

      break if !less(a, k, j) # If parent greater than child break
      swap(a, k, j)
      k = j
    end
  end

parameterized test constructor of junit java error message: Test class should have exactly one public zero-argument constructor

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public SolverTest(Board board, int expectedNumberOfMoves) {
    this.board = board;
    this.expectedNumberOfMoves = expectedNumberOfMoves;
}

public SolverTest() {
}

@RunWith(Parameterized.class)
public class SolverTest {
    final static File folder = new File("C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\ModifiedTests");
    final static String destFolder = "C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\testresults";
    final static ArrayList<Object[][]> filesList = new ArrayList<>();
    final Object currentBoard = new Object();

    @Parameterized.Parameters
    public static Iterable<Object[][]> data() {
        String path = "";
        int counter = 0;
        for (final File fileEntry : folder.listFiles()) {
            //System.out.println("processing file: " + fileEntry.getName())
            counter++;
            if (counter == 20) break;
            path = destFolder + fileEntry;
            In in = new In(fileEntry.getAbsolutePath());
            int n = in.readInt();
            int moves = in.readInt();
            int[][] tiles = new int[n][n];
            for (int i = 0; i < n; i++)
                for (int j = 0; j < n; j++)
                    tiles[i][j] = in.readInt();
            Board b = new Board(tiles);
            Object[][] fileList = new Object[][]{{b, moves}};
            filesList.add(fileList);
        }
        return filesList;
    }

    @Parameterized.Parameter(0)
    public Board board;
    @Parameterized.Parameter(1)
    public int expectedNumberOfMoves;

    public SolverTest() {
    }


    @Test
    public void test() {
        assertEquals(expectedNumberOfMoves, new Solver(board).moves());
    }

}

-----------------------

public SolverTest(Board board, int expectedNumberOfMoves) {
    this.board = board;
    this.expectedNumberOfMoves = expectedNumberOfMoves;
}

public SolverTest() {
}

@RunWith(Parameterized.class)
public class SolverTest {
    final static File folder = new File("C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\ModifiedTests");
    final static String destFolder = "C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\testresults";
    final static ArrayList<Object[][]> filesList = new ArrayList<>();
    final Object currentBoard = new Object();

    @Parameterized.Parameters
    public static Iterable<Object[][]> data() {
        String path = "";
        int counter = 0;
        for (final File fileEntry : folder.listFiles()) {
            //System.out.println("processing file: " + fileEntry.getName())
            counter++;
            if (counter == 20) break;
            path = destFolder + fileEntry;
            In in = new In(fileEntry.getAbsolutePath());
            int n = in.readInt();
            int moves = in.readInt();
            int[][] tiles = new int[n][n];
            for (int i = 0; i < n; i++)
                for (int j = 0; j < n; j++)
                    tiles[i][j] = in.readInt();
            Board b = new Board(tiles);
            Object[][] fileList = new Object[][]{{b, moves}};
            filesList.add(fileList);
        }
        return filesList;
    }

    @Parameterized.Parameter(0)
    public Board board;
    @Parameterized.Parameter(1)
    public int expectedNumberOfMoves;

    public SolverTest() {
    }


    @Test
    public void test() {
        assertEquals(expectedNumberOfMoves, new Solver(board).moves());
    }

}

-----------------------

public SolverTest(Board board, int expectedNumberOfMoves) {
    this.board = board;
    this.expectedNumberOfMoves = expectedNumberOfMoves;
}

public SolverTest() {
}

@RunWith(Parameterized.class)
public class SolverTest {
    final static File folder = new File("C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\ModifiedTests");
    final static String destFolder = "C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\testresults";
    final static ArrayList<Object[][]> filesList = new ArrayList<>();
    final Object currentBoard = new Object();

    @Parameterized.Parameters
    public static Iterable<Object[][]> data() {
        String path = "";
        int counter = 0;
        for (final File fileEntry : folder.listFiles()) {
            //System.out.println("processing file: " + fileEntry.getName())
            counter++;
            if (counter == 20) break;
            path = destFolder + fileEntry;
            In in = new In(fileEntry.getAbsolutePath());
            int n = in.readInt();
            int moves = in.readInt();
            int[][] tiles = new int[n][n];
            for (int i = 0; i < n; i++)
                for (int j = 0; j < n; j++)
                    tiles[i][j] = in.readInt();
            Board b = new Board(tiles);
            Object[][] fileList = new Object[][]{{b, moves}};
            filesList.add(fileList);
        }
        return filesList;
    }

    @Parameterized.Parameter(0)
    public Board board;
    @Parameterized.Parameter(1)
    public int expectedNumberOfMoves;

    public SolverTest() {
    }


    @Test
    public void test() {
        assertEquals(expectedNumberOfMoves, new Solver(board).moves());
    }

}

`java myClass` not finding a .class file when `java myClass.java` does? (OpenJDK)

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// Linux or MacOS
java -cp ".:foo.jar" MyClass

// Windows
java -cp ".;foo.jar" MyClass

Resizing array when elements are more than 1/2 of his size

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    public void resize(int m) { 
        int[] temp = new int[m];  // <-- this is the new double-size of m
        for(int i=0; i<hashTable.length; i++) {
            temp[i] = hashTable[i];
        }
        hashTable = new int[m];
        for(int i=0; i<temp.length; i++) {  // <-- here we go too far
            hashing(temp[i]);
        }
    }

public void resize(int m) {
    int[] oldHash = hashTable;
    hashTable = new int[m];
    for(int i=0; i<oldHash.length; i++) {
        if (oldHash[i] != 0) {     // <-- don't hash empty slots
            hashing(oldHash[i]);
        }
    }
}

-----------------------

    public void resize(int m) { 
        int[] temp = new int[m];  // <-- this is the new double-size of m
        for(int i=0; i<hashTable.length; i++) {
            temp[i] = hashTable[i];
        }
        hashTable = new int[m];
        for(int i=0; i<temp.length; i++) {  // <-- here we go too far
            hashing(temp[i]);
        }
    }

public void resize(int m) {
    int[] oldHash = hashTable;
    hashTable = new int[m];
    for(int i=0; i<oldHash.length; i++) {
        if (oldHash[i] != 0) {     // <-- don't hash empty slots
            hashing(oldHash[i]);
        }
    }
}

See all related Code Snippets

Community Discussions

Trending Discussions on algs4

Java Cannot Load Main Class Without Adding .java
compareTo with objects returns a false while it is true
How to save permutation in a Set Java
How to show top to bottom leaks in my path
How to count number of edges between red and white nodes in a graph?
How to use read file from URI using C# in PowerShell line by line?
Ruby Heapsort: `sink': undefined method `>' for nil:NilClass
parameterized test constructor of junit java error message: Test class should have exactly one public zero-argument constructor
`java myClass` not finding a .class file when `java myClass.java` does? (OpenJDK)
About exercise 1.2.9 on p.115 in "Algorithms 4th Edition" by Robert Sedgewick and Kevin Wayne

Trending Discussions on algs4

QUESTION

Java Cannot Load Main Class Without Adding .java

Asked 2021-Oct-24 at 16:08

I'm trying to run a Java class file which I've compiled, but it keeps telling me that it cannot find or load the main class.

I have a directory which looks like this:

My goal is to run the RandomWord.java file, which takes in a file input and relies on the algs4.jar file found in the .lift sub-directory. From what I've seen, to compile, I need to run the following (assuming I'm cd'ed into the hello directory):
$ javac -cp .lift/algs4.jar RandomWord.java
This should create my RandomWord.class file. Now, to run it with a txt file, for example with coin.txt, I believe I should be running the following:
$ java -cp .lift/algs4.jar RandomWord < coin.txt
However, this results in an error stating: Error: Could not find or load main class RandomWord.

I've done a ton of experimenting with this but I have no idea what's going on, but I've found that running the following works:
$ java -cp .lift/algs4.jar RandomWord.java < coin.txt
However, I believe when a .class file is created, I shouldn't be writing .java in my command line, so I'm really confused.

ANSWER

Answered 2021-Oct-24 at 16:08

Windows:

$ java -cp ".lift/algs4.jar;." RandomWord < coin.txt

Linux/Mac

$ java -cp ".lift/algs4.jar:." RandomWord < coin.txt

Current dir must be added to classpath to allow java to find classes there.

Source https://stackoverflow.com/questions/69698482

QUESTION

compareTo with objects returns a false while it is true

Asked 2021-Mar-28 at 18:26

I am trying to check whether my levelorder of my Binary Search Tree is equal to the other one. To do this, I tried to make a compareTo method. I only give equal values to the method, but it keeps on saying the condition is false. When I place breakpoints, I see that the values are still equal. I am probably not understanding it correctly. Does anyone know how to solve this?

Here is what I did, as you can see below, the compareTo returns a 1 instead of a 0:

import edu.princeton.cs.algs4.BST;
import java.util.*;

public class MyBST implements Comparable<MyBST>{

    private Object e;

    public MyBST(Object e){
        this.e = e;
    }

    private Object getE(){
        return e;
    }

    public static void main(String[] args) {

        int size = 4;

        Random r = new Random();
        Set<Integer> tes = new LinkedHashSet<>(size);
        Stack<Integer> stack = new Stack<>();

        while (tes.size() < size) {
            tes.add(r.nextInt(10));
        }

        System.out.println("possible combinations");
        Set<Stack<Integer>> combos = combos(tes, stack, tes.size());

        Object[] arr = combos.toArray();
        List<String> d = new ArrayList<>();
        for (Object s : arr) {
            String b = s.toString();
            b = b.replaceAll("\\[", "").replaceAll("\\]", "");
            d.add(b);
        }

        int index = 0;

        do {
            BST<String, Integer> bst1 = new BST<String, Integer>();
            BST<String, Integer> bst2 = new BST<String, Integer>();
            String key1 = d.get(index);
            String key2 = d.get(index);
            key1 = key1.replaceAll(" ", "");
            String[] m = key1.split(",");

            key2 = key2.replaceAll(" ", "");
            String[] n = key2.split(",");

            System.out.println("1e order");
            for (int j = 0; j < m.length; j++) {

                System.out.println(m[j]);
                bst1.put(m[j], 0);
            }

            System.out.println("2e order");
            for (int j = 0; j < n.length; j++) {

                System.out.println(n[j]);
                bst2.put(n[j], 0);
            }

            System.out.println("levelorder 1e BST");

            MyBST e = new MyBST(bst1.levelOrder());
            MyBST y = new MyBST(bst2.levelOrder());

            System.out.println(bst1.levelOrder());

            System.out.println("levelorder 2e BST");

            System.out.println(bst2.levelOrder());

            System.out.println(e.compareTo(y) + "\n");
            index++;
        } while (index < arr.length - 1);

    }
    public static Set<Stack<Integer>> combos(Set<Integer> items, Stack<Integer> stack, int size) {
        Set<Stack<Integer>> set = new HashSet<>();

        if (stack.size() == size) {
            set.add((Stack) stack.clone());
        }
        Integer[] itemz = items.toArray(new Integer[0]);
        for (Integer i : itemz) {
            stack.push(i);
            items.remove(i);
            set.addAll(combos(items, stack, size));
            items.add(stack.pop());
        }
        return set;
    }

    @Override
    public int compareTo(MyBST o) {
        if (this.e == o.e) {
            return 0;
        }
        else
            return 1;
    }
}

Here you can find the BST.java class: BST.java

And the output is something like:

The breakpoint at the compareTo method says:

ANSWER

Answered 2021-Mar-28 at 15:47

When you're using the == operator you're actually checking to see if the references point to the same object in memory. From your debugging screenshot you can see that they are not. this.e points to object Queue@817 while o.e points to Queue@819.

Source https://stackoverflow.com/questions/66843044

QUESTION

How to save permutation in a Set Java

Asked 2021-Mar-27 at 22:55

I have this method that prints my permutations of a Set I'm giving with my parameters. But I need to save them in 2 separate sets and compare them. So, for instance I have [5,6,3,1] and [5,6,1,3], by adding them in two separate BST, I can compare them by using the compareTo function to check whether their level order is the same. But I am having trouble with saving these permutations from my method into a set in my main. Does anyone know how to save these into a set?

What I have now:

import edu.princeton.cs.algs4.BST;

import java.util.*;

public class MyBST {
    public static void main(String[] args) {
        int size = 4;
        BST<Integer, Integer> bst1 = new BST<Integer, Integer>();
        BST<Integer, Integer> bst2 = new BST<Integer, Integer>();
        Random r = new Random();
        Set<Integer> tes = new LinkedHashSet<>(size);
        Stack<Integer> stack = new Stack<>();
        while (tes.size() < size) {
            tes.add(r.nextInt(10));
        }
        System.out.println(tes);
        System.out.println("possible combinations");
        Iterator<Integer> it = tes.iterator();
        for (int i = 0; i < tes.toArray().length; i++) {
            Integer key = it.next();
            bst1.put(key, 0);
        }
        combos(tes, stack, tes.size());
    }
}

and here is the method I use:

public static void combos(Set<Integer> items, Stack<Integer> stack, int size) {
    if (stack.size() == size) {
        System.out.println(stack);
    }
    Integer[] itemz = items.toArray(new Integer[0]);
    for (Integer i : itemz) {
        stack.push(i);
        items.remove(i);
        combos(items, stack, size);
        items.add(stack.pop());
    }
}

And this is the output:

ANSWER

Answered 2021-Mar-27 at 22:55

I'm not sure if I understood your idea but maybe this will help:

Yours combos method will return set of all permutations (as Stacks)

...
        for (int i = 0; i < tes.toArray().length; i++) {
            Integer key = it.next();
            bst1.put(key, 0);
        }
        Set<Stack<Integer>> combos = combos(tes, stack, tes.size()); //there you have set with all Stacks
    }
}

    public static Set<Stack<Integer>> combos(Set<Integer> items, Stack<Integer> stack, int size) {
    Set<Stack<Integer>> set = new HashSet<>();

    if(stack.size() == size) {
        System.out.println(stack.to);
        set.add((Stack) stack.clone());
    }

    Integer[] itemz = items.toArray(new Integer[0]);
    for(Integer i : itemz) {
        stack.push(i);
        items.remove(i);
        set.addAll(combos(items, stack, size));
        items.add(stack.pop());
    }
    return set;
}

Source https://stackoverflow.com/questions/66836224

QUESTION

How to show top to bottom leaks in my path

Asked 2021-Feb-02 at 16:19

I used the percolation class from the algs4.jar library, where you can simulate a whole labyrinth and see where the leaks are. I want to show the leaks that are from top to bottom, but now I get to see all of the leaks.

Does anyone know how I can see only the leaks that are percolations?

I thought maybe using dfs from the flow method in de Percolation.java class, and say something like only show when index i in rows is maxlength and marked but I don't really know how to say that, because I am not sure if this statement will show the entire leak of just the max length leak.

code I run AssignmentTwo.java:

import edu.princeton.cs.algs4.StdDraw;

public class AssignmentTwo {
    public static void main(String[] args) {
        int n      = 500;
        double p   = 0.60;
        int trials = 20;

        // repeatedly created n-by-n matrices and display them using standard draw
        StdDraw.enableDoubleBuffering();
        for (int t = 0; t < trials; t++) {
            boolean[][] open = Percolation.random(n, p);
            StdDraw.clear();
            StdDraw.setPenColor(StdDraw.PINK);
            Percolation.show(open, false);
            StdDraw.setPenColor(StdDraw.BLACK);
            boolean[][] full = Percolation.flow(open);
            Percolation.show(full, true);
            StdDraw.show();
            StdDraw.pause(1000);
        }
    }
}

and this is the Percolation.java class:

import edu.princeton.cs.algs4.StdArrayIO;
import edu.princeton.cs.algs4.StdDraw;
import edu.princeton.cs.algs4.StdOut;
import edu.princeton.cs.algs4.StdRandom;

public class Percolation {

    // given an n-by-n matrix of open sites, return an n-by-n matrix
    // of sites reachable from the top
    public static boolean[][] flow(boolean[][] isOpen) {
        int n = isOpen.length;
        boolean[][] isFull = new boolean[n][n];
        for (int j = 0; j < n; j++) {
            flow(isOpen, isFull, 0, j);
        }
        return isFull;
    }

    // determine set of full sites using depth first search
    public static void flow(boolean[][] isOpen, boolean[][] isFull, int i, int j) {
        int n = isOpen.length;

        // base cases
        if (i < 0 || i >= n) return;    // invalid row
        if (j < 0 || j >= n) return;    // invalid column
        if (!isOpen[i][j]) return;      // not an open site
        if (isFull[i][j]) return;       // already marked as full

        // mark i-j as full
        isFull[i][j] = true;

        flow(isOpen, isFull, i+1, j);   // down
        flow(isOpen, isFull, i, j+1);   // right
        flow(isOpen, isFull, i, j-1);   // left
        flow(isOpen, isFull, i-1, j);   // up
    }


    // does the system percolate?
    public static boolean percolates(boolean[][] isOpen) {
        int n = isOpen.length;
        boolean[][] isFull = flow(isOpen);
        for (int j = 0; j < n; j++) {
            if (isFull[n-1][j]) return true;
        }
        return false;
    }

    // draw the n-by-n boolean matrix to standard draw
    public static void show(boolean[][] a, boolean which) {
        int n = a.length;
        StdDraw.setXscale(-1, n);
        StdDraw.setYscale(-1, n);
        for (int i = 0; i < n; i++)
            for (int j = 0; j < n; j++)
                if (a[i][j] == which)
                    StdDraw.filledSquare(j, n-i-1, 0.5);
    }

    // return a random n-by-n boolean matrix, where each entry is
    // true with probability p
    public static boolean[][] random(int n, double p) {
        boolean[][] a = new boolean[n][n];
        for (int i = 0; i < n; i++)
            for (int j = 0; j < n; j++)
                a[i][j] = StdRandom.bernoulli(p);
        return a;
    }

    // test client
    public static void main(String[] args) {
        boolean[][] isOpen = StdArrayIO.readBoolean2D();
        StdArrayIO.print(flow(isOpen));
        StdOut.println(percolates(isOpen));
    }

}

ANSWER

Answered 2021-Feb-02 at 16:19

It seems that disabling double buffering will get you the result you want:

public class AssignmentTwo {
    public static void main(String[] args) {
        int n      = 500;
        double p   = 0.60;

        StdDraw.enableDoubleBuffering();
        boolean[][] open = Percolation.random(n, p);
        StdDraw.clear();
        StdDraw.setPenColor(StdDraw.PINK);
        Percolation.show(open, false);
        StdDraw.setPenColor(StdDraw.BLACK);
        StdDraw.show();
        StdDraw.disableDoubleBuffering();
         boolean[][] full = Percolation.flow(open);
         Percolation.show(full, true);
    }
}

Source https://stackoverflow.com/questions/65994196

QUESTION

How to count number of edges between red and white nodes in a graph?

Asked 2020-Oct-07 at 19:35

I would like to count how many edges there are that goes between a white and a red node. The red nodes are the ones in the new int[] in the main method.

Provided code for the assignment:

import edu.princeton.cs.algs4.Graph;

public class RedWhite {
    public static int count(Graph G, int[] rednodes) {
        int rw_count = 0;

        // Count how many of the edges in G connect a white node (one that
        // isn't in rednodes) with a red node (one that is in rednodes).

        return rw_count;
    }    
}

and

import edu.princeton.cs.algs4.Graph;

public class TestRW {
    public static void main(String[] args) {
        Graph G = new Graph(13);
        G.addEdge(0, 1);
        G.addEdge(3, 2);
        G.addEdge(3, 5);
        G.addEdge(4, 3);
        G.addEdge(4, 2);
        G.addEdge(6, 9);
        G.addEdge(8, 7);
        G.addEdge(8, 9);
        G.addEdge(9, 11);
        G.addEdge(10, 12);
        G.addEdge(11, 12);
        G.addEdge(12, 9);

        System.out.println(RedWhite.count(G, new int[] { 3 }));                                        // should print 3
        System.out.println(RedWhite.count(G, new int[] { 3, 4, 2 }));                                  // should print 1
        System.out.println(RedWhite.count(G, new int[] { 3, 4, 2, 11, 12 }));                          // should print 4
        System.out.println(RedWhite.count(G, new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 })); // should print 0
        System.out.println(RedWhite.count(G, new int[] {  }));                                         // should print 0
    }
}

I am having trouble traversing the graph and I don't know how to use rednodes[] to compare to the graph. When running my attempted code below I get errors in the marked and count methods.

Any help is appreciated.

import edu.princeton.cs.algs4.Graph;

public class RedWhite {
    private static boolean[] marked;

    public RedWhite(Graph G, int s) {
        marked = new boolean[G.V()];
        dfs(G, s);
    }

    public static int count(Graph G, int[] rednodes) {
        int rw_count = 0;

        for (int w : G.adj(rednodes.length))
        {
            if (marked(w)) {
                rw_count++;
            }
        }

        // Count how many of the edges in G connect a white node (one that
        // isn't in rednodes) with a red node (one that is in rednodes).

        return rw_count;
    }
   
    private void dfs(Graph G, int v) {
        marked[v] = true;
        for (int w : G.adj(v)) {
            if (!marked[w]) {
                dfs(G, w);
            }
        }
    }

    public static boolean marked(int v) {
        return marked[v];
    }

    public static void main(String[] args) {
        Graph G = new Graph(13);
    G.addEdge(0, 1);
    G.addEdge(3, 2);
    G.addEdge(3, 5);
    G.addEdge(4, 3);
    G.addEdge(4, 2);
    G.addEdge(6, 9);
    G.addEdge(8, 7);
    G.addEdge(8, 9);
    G.addEdge(9, 11);
    G.addEdge(10, 12);
    G.addEdge(11, 12);
    G.addEdge(12, 9);

    System.out.println(RedWhite.count(G, new int[] { 3 }));                                        // should print 3
    System.out.println(RedWhite.count(G, new int[] { 3, 4, 2 }));                                  // should print 1
    System.out.println(RedWhite.count(G, new int[] { 3, 4, 2, 11, 12 }));                          // should print 4
    System.out.println(RedWhite.count(G, new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 })); // should print 0
    System.out.println(RedWhite.count(G, new int[] {  }));                                         // should print 0
    }
}

ANSWER

Answered 2020-Oct-07 at 19:14

To be fair I code in C++, not java, but here's a question: Why does your marked() function return the value of a marked array? Wouldn't it make more sense to use that array directly?

For the time being I can tell you are using a DFS to traverse the graph correctly. I am not sure, however, why you are traversing the graph at all.

I am sorry, but this is going to be one of these "don't do this, do that instead" answers.

If you are looking for a linear solution (for one execution of the count method), you better just create an array which, for each node holds info about whether it is white or red. I'd recommend filling it with zeroes, and then going over the rednodes array to change appropriate values to 1.

Next, you declare a result variable equal to zero, which will count the number of edges which connect to nodes of different colours. You iterate over all the edges, and check if the vertices they connect are of varying colours. If so, increment the result variable.

Source https://stackoverflow.com/questions/64246492

QUESTION

How to use read file from URI using C# in PowerShell line by line?

Asked 2020-Sep-25 at 03:48

Am trying to incorporate some C# code into my PowerShell, as I am still learning C# and getting a foothold on learning a new language.

I am able to open a file locally on my computer and read it line by line. But cannot seem to work out how to open a file from the internet and parse it line by line.

This works to read the file line by line, and allows me to take action on the line items in the loop.

$f = 'C:\tmp\tinyUF.txt'
$reader = [System.IO.File]::OpenText($f)
while (-not($reader.EndOfStream)) {
    $line = $reader.ReadLine()
}
$x.Close()

This doesn't work, so I did some research and found that [System.IO.File] is not going to be able to read $f as a feed.

$f = (Invoke-WebRequest -Uri https://algs4.cs.princeton.edu/15uf/tinyUF.txt).Content
$reader = [System.IO.File]::OpenText($f)
while (-not($reader.EndOfStream)) {
    $line = $reader.ReadLine()
}
$x.Close()

So I looked at different ways to solve my own problem and learn along the way:

1. Using `[System.Net.WebRequest]`

Created a $reader object and pointed it to the URL. But I can't see a method that allows me to read the data. I was hoping it would work like Invoke-WebRequest -Uri 'https://algs4.cs.princeton.edu/15uf/tinyUF.txt').Content and I would be able to parse the data, but that didn't work out.

$reader = [System.Net.WebRequest]::Create('https://algs4.cs.princeton.edu/15uf/tinyUF.txt')

2. Using `[System.Net.WebRequest]`

$reader = [System.Net.WebRequest]::Create('https://algs4.cs.princeton.edu/15uf/tinyUF.txt')

3. Using `[System.Net.WebClient]`

I thought maybe I could create a WebClient and point it to the URI as shown here

So I put that together, and got the error on the second line:

$reader = [System.Net.WebClient]::new('https://algs4.cs.princeton.edu/15uf/tinyUF.txt')
MethodException: Cannot find an overload for "new" and the argument count: "1".

I tried some of the other solutions listed there, but didn't quite understand them.

ANSWER

Answered 2020-Jul-06 at 16:20

Actually, I found a working solution.

I was re-reading and testing before posting this question, I came up with a method to solve my own predicament. In the event anyone else is interested, here is the solution:

# Set $f to point to the target file on the web
$f = 'https://algs4.cs.princeton.edu/15uf/tinyUF.txt'

# $wc to represent the WebClient
$wc = [System.Net.WebClient]::new()

# Create a stream object, using the .OpenRead method on $f
$stream = $wc.OpenRead($f)

# Create a reader of the stream using System.IO.StreamReader
$reader = [System.IO.StreamReader]($stream)

# ForEach-Object didn't play nice, so using while until it displays the last line of the file
while (-not($reader.EndOfStream)) {
    $line = $reader.ReadLine();
    $line
}

# Close the StreamReader
$reader.Close()

# Dispose of the WebClient
$wc.Dispose()

Source https://stackoverflow.com/questions/62760272

QUESTION

Ruby Heapsort: `sink': undefined method `>' for nil:NilClass

Asked 2020-Sep-01 at 12:37

I'm currently working on Robert Sedgewicks Algorithm's book. I'm trying to implement Heap sort but I'm coming across an error

'sink': undefined method >' for nil:NilClass

This error happens because of the when the array is pass to the sort method it has 11 elements at 0 index. when it swaps index n (the number of elements in the array) with 1 is comparing nil with a string. Meaning n is 11 but there is no 11 index because the array index starts at 0.

Here is the Java implementation for the Heap sort method in the book:

 public static void sort(Comparable[] a)
  {
     int N = a.length;
     for (int k = N/2; k >= 1; k--)
        sink(a, k, N);
     while (N > 1)
     {
        exch(a, 1, N--);
        sink(a, 1, N);
     }
}

Now here is the implementation in Ruby:

  def sort(a)
    n = a.length
    k = n/2
    while k >= 1
      sink(a, k, n)
      k -= 1
    end
    
    while n > 1
      swap(a, 1, n)
      n -= 1
      sink(a, 1, n)
    end
    a
  end

Now, in the book the array disregards the position a[0] and starts at a[1] but I'm a bit unclear how that is being done in the sort method in the Java implementation. It is also a bit strange to me that the method would required to be pass an array starting at index 1. So my understanding is that the sort method in the Java implementation will set the array.

Notice in the example how the first element in the array starts at index 1 a[1]. Is this being done in the sort method? Meaning rearranging the array to start at index 1?

Is the Ruby implementation of sort in Ruby correct? Or is there an error?

Full implementation of Heap sort.

class Heap
  # Trickledown
  def sink(a, k, n)
    while 2 * k <= n
      j = 2 * k # child

      if !a[j + 1].nil? # check if there is a right child
        j += 1 if j > 1 && less(a, j, j + 1) # if left child less than right child
      end

      break if !less(a, k, j) # If parent greater than child break

      swap(a, k, j)
      k = j
    end
  end

  def sort(a)
    n = a.length
    k = n / 2

    while k >= 1
      sink(a, k, n)
      k -= 1
    end

    while n > 1
      swap(a, 1, n)
      n -= 1
      sink(a, 1, n)
    end
    a
  end

  def less(pq, i, j)
    pq[i - 1] < pq[j - 1]
  end

  def swap(a, i, j)
    temp = a[i - 1]
    a[i - 1] = a[j - 1]
    a[j - 1] = temp
  end
end

input = ["S", "O", "R", "T", "E", "X", "A", "M", "P", "L", "E"]

heap = Heap.new
p heap.sort(input)

When I edit the less and swap methods to address the off by one index in the array it those works correctly on some but not all the elements. If you check the last line is a TEST to run the script but it returns:

["A", "M", "E", "L", "E", "O", "P", "R", "S", "T", "X"]

But the correct answer is

 ["A", "E", "E", "L", "M", "O", "P", "R", "S", "T", "X"]

ANSWER

Answered 2020-Sep-01 at 12:37

The error was coming from the following line:

if !a[j + 1].nil? # check if there is a right child

This line checks if a right node exist. The problem in the heap sort implementation is that we are decreasing n by one in each iteration.

 while n > 1
    swap(a, 1, n)
    n -= 1
    sink(a, 1, n)
 end

Thus we are not keeping track of the elements store in the array that are over index n. Although the array has values stored in the array we are treating only the a[0] to a[n] as a heap.

there for I shouldn't check to see if a[j + 1] is nil rather see if j + 1 is less than or equal to n.

  def sink(a, k, n)
    while 2 * k <= n
      j = 2 * k # child

      if j + 1 <= n # check if there is a right child
        j += 1 if j > 1 && less(a, j, j + 1) # if left child less than right child
      end

      break if !less(a, k, j) # If parent greater than child break
      swap(a, k, j)
      k = j
    end
  end

Source https://stackoverflow.com/questions/63634906

QUESTION

parameterized test constructor of junit java error message: Test class should have exactly one public zero-argument constructor

Asked 2020-Jul-14 at 02:11

I can really use some help with this parameterized test case I am trying to create. No matter what kind of constructor I create the IDE gives an error message. Here is my code:

@RunWith(Parameterized.class)
public class SolverTest {
    final static File folder = new File("C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\ModifiedTests");
    final static String destFolder = "C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\testresults";
    final static ArrayList<Object[][]> filesList = new ArrayList<>();
    final Object currentBoard = new Object();

    @Parameterized.Parameters
    public static Iterable<Object[][]> data() {
        String path = "";
        int counter = 0;
        for (final File fileEntry : folder.listFiles()) {
            //System.out.println("processing file: " + fileEntry.getName())
            counter++;
            if (counter == 20) break;
            path = destFolder + fileEntry;
            In in = new In(fileEntry.getAbsolutePath());
            int n = in.readInt();
            int moves = in.readInt();
            int[][] tiles = new int[n][n];
            for (int i = 0; i < n; i++)
                for (int j = 0; j < n; j++)
                    tiles[i][j] = in.readInt();
            Board b = new Board(tiles);
            Object[][] fileList = new Object[][]{{b, moves}};
            filesList.add(fileList);
        }
        return filesList;
    }

    @Parameterized.Parameter(0)
    private Board board;
    @Parameterized.Parameter(1)
    private int expectedNumberOfMoves;

    public SolverTest(Board board, int expectedNumberOfMoves) {
        this.board = board;
        this.expectedNumberOfMoves = expectedNumberOfMoves;
    }


    @Test
    public void test() {
        assertEquals(expectedNumberOfMoves, new Solver(board).moves());
    }

}

I have tried different ways of creating a 1 parameter, 2, and no parameter constructors. But I have never seen this type of issue or what the solution might be. I am following this link and this tutorial. This is my first parameterized test, and debug does not seem to provide much for me either. I also saw these links, but they did not help. I can provide the code for the rest of the project also on GitHub or gist. I did debug my code through creating the fileList properly, but I know little about what happens to it afterwards or what needs to happen. Here is an excerpt of the error:

java.lang.Exception: Test class should have exactly one public zero-argument constructor

    at org.junit.runners.BlockJUnit4ClassRunner.validateZeroArgConstructor(BlockJUnit4ClassRunner.java:171)
    at org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParameters.validateConstructor(BlockJUnit4ClassRunnerWithParameters.java:90)
    at org.junit.runners.BlockJUnit4ClassRunner.collectInitializationErrors(BlockJUnit4ClassRunner.java:127)
    at org.junit.runners.ParentRunner.validate(ParentRunner.java:416)
    at org.junit.runners.ParentRunner.<init>(ParentRunner.java:84)
    at org.junit.runners.BlockJUnit4ClassRunner.<init>(BlockJUnit4ClassRunner.java:65)
    at org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParameters.<init>(BlockJUnit4ClassRunnerWithParameters.java:27)
    at org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParametersFactory.createRunnerForTestWithParameters(BlockJUnit4ClassRunnerWithParametersFactory.java:16)
    at org.junit.runners.Parameterized.createRunnersForParameters(Parameterized.java:313)
    at org.junit.runners.Parameterized.<init>(Parameterized.java:248)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
    at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:104)
    at org.junit.vintage.engine.discovery.DefensiveAllDefaultPossibilitiesBuilder$DefensiveAnnotatedBuilder.buildRunner(DefensiveAllDefaultPossibilitiesBuilder.java:113)

Here is the latest version of my code:

package assignments;

import edu.princeton.cs.algs4.In;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;

import java.io.File;
import java.util.ArrayList;

import static junit.framework.TestCase.assertEquals;

@RunWith(Parameterized.class)
public class SolverTest {
    final static File folder = new File("C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\ModifiedTests");
    final static String destFolder = "C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\testresults";
    final static ArrayList<Object[][]> filesList = new ArrayList<>();
    final Object currentBoard = new Object();

    @Parameterized.Parameters
    public static Iterable<Object[][]> data() {
        String path = "";
        int counter = 0;
        for (final File fileEntry : folder.listFiles()) {
            //System.out.println("processing file: " + fileEntry.getName())
            counter++;
            if (counter == 20) break;
            path = destFolder + fileEntry;
            In in = new In(fileEntry.getAbsolutePath());
            int n = in.readInt();
            int moves = in.readInt();
            int[][] tiles = new int[n][n];
            for (int i = 0; i < n; i++)
                for (int j = 0; j < n; j++)
                    tiles[i][j] = in.readInt();
            Board b = new Board(tiles);
            Object[][] fileList = new Object[][]{{b, moves}};
            filesList.add(fileList);
        }
        return filesList;
    }

    @Parameterized.Parameter(0)
    public Board board;
    @Parameterized.Parameter(1)
    public int expectedNumberOfMoves;

    public SolverTest() {
    }


    @Test
    public void test() {
        assertEquals(expectedNumberOfMoves, new Solver(board).moves());
    }

}

Here is a pic of the debug session showing everything I want in the file list. Some how the board object does not transfer to my Solver constructor.

ANSWER

Answered 2020-Jul-14 at 02:11

Here is what the no-arg constructor error means.

The constructor in the test class is the following:

public SolverTest(Board board, int expectedNumberOfMoves) {
    this.board = board;
    this.expectedNumberOfMoves = expectedNumberOfMoves;
}

That takes 2 arguments, so is not a no-arg constructor. The following is a no-arg constructor:

public SolverTest() {
}

Removing the 2-arg constructor will work, so this does not need to be explicitly listed, because the java compiler will add the default no-arg constructor automatically.

HOWEVER the reason for the error is a mix of 2 approaches for the Parameterized test class.

EITHER use a no-arg constructor with the @Parameterized.Parameters fields (which need to be public and not private, by the way), OR remove those fields and use the construct with arguments that take the parameters.

Here is the code modified to use the first approach (that is, with the @Parameterized.Parameters fields):

@RunWith(Parameterized.class)
public class SolverTest {
    final static File folder = new File("C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\ModifiedTests");
    final static String destFolder = "C:\\Users\\Azizam\\IdeaProjects\\EightPuzzle\\src\\testresults";
    final static ArrayList<Object[][]> filesList = new ArrayList<>();
    final Object currentBoard = new Object();

    @Parameterized.Parameters
    public static Iterable<Object[][]> data() {
        String path = "";
        int counter = 0;
        for (final File fileEntry : folder.listFiles()) {
            //System.out.println("processing file: " + fileEntry.getName())
            counter++;
            if (counter == 20) break;
            path = destFolder + fileEntry;
            In in = new In(fileEntry.getAbsolutePath());
            int n = in.readInt();
            int moves = in.readInt();
            int[][] tiles = new int[n][n];
            for (int i = 0; i < n; i++)
                for (int j = 0; j < n; j++)
                    tiles[i][j] = in.readInt();
            Board b = new Board(tiles);
            Object[][] fileList = new Object[][]{{b, moves}};
            filesList.add(fileList);
        }
        return filesList;
    }

    @Parameterized.Parameter(0)
    public Board board;
    @Parameterized.Parameter(1)
    public int expectedNumberOfMoves;

    public SolverTest() {
    }


    @Test
    public void test() {
        assertEquals(expectedNumberOfMoves, new Solver(board).moves());
    }

}

Source https://stackoverflow.com/questions/62881330

QUESTION

`java myClass` not finding a .class file when `java myClass.java` does? (OpenJDK)

Asked 2020-Jun-18 at 20:33

When I'm running java -cp foo.jar MyClass I keep getting the error:

Error: Could not find or load main class PrimVsKruskal
Caused by: java.lang.ClassNotFoundException: PrimVsKruskal

But when I run java -cp foo.jar MyClass.java it works fine. This has been happening in different files in different directories and yes, I have run javac -cp foo.jar MyClass.java to generate the .class bytecode.

I've also tried running java -cp foo.jar MyClass.class (same error but with '.class' at the end of each line) and have become fairly certain I just don't understand the java command very well. When I delete the MyClass.class file and run java -cp foo.jar MyClass.java it runs fine which seems to suggest that java is compiling its own bytecode when run with a .java file rather than just interpreting the bytecode. Is this true?

Any help with this, or just a better understanding of the java than what I can glean from the man pages would be very much appreciated! I've searched around online but when I have to search "java command" nothing relevant has come up.

Not sure if it matters, but I'm running OpenJDK version "11.0.7" 2020-04-14 on Ubuntu 18.04.4.

Thanks!

============

Edit due to comment:

The .jar file is algs4.jar from https://algs4.cs.princeton.edu/code/. A minimum working example that is giving me these same errors is:

import edu.princeton.cs.algs4.*;

public class MyClass{

   public static void main(String[] args) {
        System.out.println( "I am working! ");
    }
}

ANSWER

Answered 2020-Jun-18 at 20:33

Your problem is that when you include the -cp option you are overriding the class path.

So if your .class file is in the current path you must write:

// Linux or MacOS
java -cp ".:foo.jar" MyClass

// Windows
java -cp ".;foo.jar" MyClass

Source https://stackoverflow.com/questions/62458602

QUESTION

About exercise 1.2.9 on p.115 in "Algorithms 4th Edition" by Robert Sedgewick and Kevin Wayne

Asked 2020-Jun-06 at 14:09

I am reading "Algorithms 4th Edition" by Robert Sedgewick and Kevin Wayne.

The following code is my answer for the exercise 1.2.9 on p.115.

I expect this code prints the total number of keys examined during all searches but this code doesn't print the value of the counter.

Why?

package exercise.chapter2.section2;

import java.util.Arrays;

import edu.princeton.cs.algs4.Counter;
import edu.princeton.cs.algs4.In;
import edu.princeton.cs.algs4.StdIn;
import edu.princeton.cs.algs4.StdOut;

public class Ex1_2_09 {

    public static int indexOf(int[] a, int key, Counter c) {
        int lo = 0;
        int hi = a.length - 1;
        while (lo <= hi) {
            // Key is in a[lo..hi] or not present.
            c.increment();
            int mid = lo + (hi - lo) / 2;
            if      (key < a[mid]) hi = mid - 1;
            else if (key > a[mid]) lo = mid + 1;
            else return mid;
        }
        return -1;
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        // read the integers from a file
        In in = new In(args[0]);
        int[] whitelist = in.readAllInts();

        // sort the array
        Arrays.sort(whitelist);

        Counter c = new Counter("- the total number of keys examinded during all searches");
        // read integer key from standard input; print if not in whitelist
        while (!StdIn.isEmpty()) {
            int key = StdIn.readInt();
            if (indexOf(whitelist, key, c) == -1) {
                StdOut.println(key);
            }
        }
        StdOut.println(c);  //I want to print c, but this code doesn't print it. Why?
    }

}

ANSWER

Answered 2020-Jun-06 at 13:58

StdIn will never be empty. It's your keyboard, it can only be waiting for your input. You need to add something to end the loop, such as the user entering some specific key, like q or some other key that won't affect the function of the rest of your program.

Source https://stackoverflow.com/questions/62232464

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