interview | Interview questions

by mission-peace Java Version: Current License: Apache-2.0

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kandi X-RAY | interview Summary

interview is a Java library typically used in MongoDB applications. interview has no vulnerabilities, it has build file available, it has a Permissive License and it has medium support. However interview has 45 bugs. You can download it from GitHub.

Interview questions

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kandi-support Support

interview has a medium active ecosystem.
It has 9741 star(s) with 4821 fork(s). There are 1037 watchers for this library.
It had no major release in the last 12 months.
There are 57 open issues and 25 have been closed. On average issues are closed in 27 days. There are 109 open pull requests and 0 closed requests.
It has a neutral sentiment in the developer community.
The latest version of interview is current.

interview Support

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interview Support

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quality kandi Quality

interview has 45 bugs (4 blocker, 1 critical, 27 major, 13 minor) and 3103 code smells.

interview Quality

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interview Quality

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Average in #Java

security Security

interview has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
interview code analysis shows 0 unresolved vulnerabilities.
There are 16 security hotspots that need review.

interview Security

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interview Security

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license License

interview is licensed under the Apache-2.0 License. This license is Permissive.
Permissive licenses have the least restrictions, and you can use them in most projects.

interview License

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interview License

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Average in #Java

build Reuse

interview 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.
interview saves you 14814 person hours of effort in developing the same functionality from scratch.
It has 29606 lines of code, 2042 functions and 604 files.
It has medium code complexity. Code complexity directly impacts maintainability of the code.

interview Reuse

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interview Reuse

Best in #Java

Average in #Java

Top functions reviewed by kandi - BETA

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

Start phase .
Returns the largest multiple of the given array
Checks if the input is schedramble
Returns the max chain of two nodes .
Returns the longest palindic char in linear form .
Gets the equation .
Justify one word .
Justify words .
Finds sub - square in the input string .
Get the skyline for the given buildings

interview Key Features

Interview questions

interview Examples and Code Snippets

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How it is possible to cast parent to child in c#

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if (p is Child child) {
    child.DriveParentsToDespair();
}

How to resolve Custom Sort Runtime error 1004

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Sub custom_sort()
    Dim vCustom_Sort As Variant, rr As Long

    vCustom_Sort = Array("Published", "Submitted", "Distributed", "Amending", "Awaiting Sign-off", "Materials Drafting", "Working Up", "Arranging Interview", "Sourcing Information/Images", "Confirmed", "Pitched", "On Hold", "Archive")
    Application.AddCustomList ListArray:=vCustom_Sort

    With ActiveWorkbook.Worksheets("Activity")
        .Sort.SortFields.Clear
        rr = .Cells(.Rows.Count, "B").End(xlUp).Row
        With .Range("A2:L" & rr)
            .Sort Key1:=.Columns(2), Order1:=xlAscending, DataOption1:=xlSortNormal, _
                        Orientation:=xlTopToBottom, Header:=xlYes, MatchCase:=False, _
                        OrderCustom:=Application.CustomListCount + 1
        End With
        .Sort.SortFields.Clear
    End With
End Sub

Sub custom_sort_table()

Dim ws As Worksheet
Set ws = ActiveSheet
Dim sortcol As Range
Dim tbl As ListObject
Dim vCustom_Sort As Variant

Set tbl = ws.ListObjects("Table1") 'Set/adjust table name
Set sortcol = Range("Table1[Status]") 'Set/adjust table column you want to sort (i.e. table name + column name)

vCustom_Sort = Array("Published", "Submitted", "Distributed", "Amending", "Awaiting Sign-off", "Materials Drafting", "Working Up", "Arranging Interview", "Sourcing Information/Images", "Confirmed", "Pitched", "On Hold", "Archive")
Application.AddCustomList ListArray:=vCustom_Sort

With ActiveWorkbook.Worksheets("Activity")
    With tbl.Sort 'sort table
        .SortFields.Clear 'clear previous sorting
        .SortFields.Add Key:=sortcol, SortOn:=xlSortOnValues, Order:=xlAscending, CustomOrder:=Application.CustomListCount
        .Header = xlYes 'Ignore heading
        .Apply 'Need to apply sorting, otherwise it won't change sort
    End With
End With

End Sub

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

Sub custom_sort()
    Dim vCustom_Sort As Variant, rr As Long

    vCustom_Sort = Array("Published", "Submitted", "Distributed", "Amending", "Awaiting Sign-off", "Materials Drafting", "Working Up", "Arranging Interview", "Sourcing Information/Images", "Confirmed", "Pitched", "On Hold", "Archive")
    Application.AddCustomList ListArray:=vCustom_Sort

    With ActiveWorkbook.Worksheets("Activity")
        .Sort.SortFields.Clear
        rr = .Cells(.Rows.Count, "B").End(xlUp).Row
        With .Range("A2:L" & rr)
            .Sort Key1:=.Columns(2), Order1:=xlAscending, DataOption1:=xlSortNormal, _
                        Orientation:=xlTopToBottom, Header:=xlYes, MatchCase:=False, _
                        OrderCustom:=Application.CustomListCount + 1
        End With
        .Sort.SortFields.Clear
    End With
End Sub

Sub custom_sort_table()

Dim ws As Worksheet
Set ws = ActiveSheet
Dim sortcol As Range
Dim tbl As ListObject
Dim vCustom_Sort As Variant

Set tbl = ws.ListObjects("Table1") 'Set/adjust table name
Set sortcol = Range("Table1[Status]") 'Set/adjust table column you want to sort (i.e. table name + column name)

vCustom_Sort = Array("Published", "Submitted", "Distributed", "Amending", "Awaiting Sign-off", "Materials Drafting", "Working Up", "Arranging Interview", "Sourcing Information/Images", "Confirmed", "Pitched", "On Hold", "Archive")
Application.AddCustomList ListArray:=vCustom_Sort

With ActiveWorkbook.Worksheets("Activity")
    With tbl.Sort 'sort table
        .SortFields.Clear 'clear previous sorting
        .SortFields.Add Key:=sortcol, SortOn:=xlSortOnValues, Order:=xlAscending, CustomOrder:=Application.CustomListCount
        .Header = xlYes 'Ignore heading
        .Apply 'Need to apply sorting, otherwise it won't change sort
    End With
End With

End Sub

Calculate average of any two numbers in a given array in JavaScript?

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const
    values = [4, 5, 10, 9, 8];

for (let i = 0, l = values.length - 1; i < l; i++) {
    for (j = i + 1; j < values.length; j++) {
        const average = (values[i] + values[j]) / 2;
        console.log(values[i], values[j], '|', average, '|', ...values.filter(v => v > average));
    }
}

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

function solve(arr) {
    arr.sort(function (a, b) { return a - b });
    let firstMinimum = arr[0];
    let secondMinimun = arr[1];
    let avg = (firstMinimum + secondMinimun) / 2;

    for (let i = 0; i < arr.length; i++) {
        if (arr[i] > avg) console.log(arr[i]);
    }
}
solve([4, 5, 10, 9, 8]);

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

let arr = [4,5,10,9,8]
arr.sort((a,b) => a-b)    // sorted array

function greaterThanAverage(x,y){
    let average = (x+y)/2
    let index = arr.findIndex(e => e > average )
    return arr.slice(index == -1 ? arr.length : index)
}

console.log(greaterThanAverage(5,9))
console.log(greaterThanAverage(10,9))
console.log(greaterThanAverage(5,4))
console.log(greaterThanAverage(30,4))

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

    const values = [4, 5, 10, 9, 8];
    const minValue = Math.min(...values);
    values.splice(values.indexOf(minValue),1);
    const secondMinValue = Math.min(...values);
    const minAverage = (minValue + secondMinValue)/2;
    const result = values.filter(val => val > minAverage);

Why ambiguous reference error while using Left without parameters type?

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scala> for (v1 <- Right(2)) yield v1
res13: scala.util.Either[Nothing,Int] = Right(2)

for {
  v1 <- Left[Int,Int](1)
  v2 <- Right[Int,Int](2)
  v3 <- Right[Int,Int](3)
  v4 <- Left[Int,Int](4)
} yield v1 + v2 + v3 + v4

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

scala> for (v1 <- Right(2)) yield v1
res13: scala.util.Either[Nothing,Int] = Right(2)

for {
  v1 <- Left[Int,Int](1)
  v2 <- Right[Int,Int](2)
  v3 <- Right[Int,Int](3)
  v4 <- Left[Int,Int](4)
} yield v1 + v2 + v3 + v4

Counting total number of paper pieces

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int func(int a, int b, int c, int d, int n) {
 if (n == 0) return (a + b + c + d);
 if (n % 2 == 0) return func(a + b, a, c + d, c, n - 1);
 else return func(a + c, b + d, a, b, n - 1);
}

Permutations of the same 4 digits resulting into 2 pairs

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def xnor_pairs(seq):
    # Create two pointers: one on the start and another at the end
    i0 = 0
    i1 = len(seq) - 1
    
    pairs = []
    
    # Repeat this until the start pointer has not reached the end
    while i0 < len(seq) - 1:
        a, b = seq[i0], seq[i1]
        
        # If the start and end indexes are equal
        if i0 == i1:
            # Move the start pointer one position closer to the end
            i0 += 1
            # Move the end pointer back to the end
            i1 = len(seq) - 1
            
            continue

        # If the condition is satisfied (a XNOR b == -1)
        if ~(a ^ b) == -1:
            # Append to the pairs
            pairs.append((a, b))
        
        # Move the end pointer one position closer to the start
        i1 -= 1
        
    return pairs

print(xnor_pairs([1, 2, 3, 3, 4, 4, 4, 10, 10, 10]))
# Output: [(3, 3), (4, 4), (4, 4), (4, 4), (10, 10), (10, 10), (10, 10)]

Async operations when instance created

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    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { return this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) =>  this.myAsyncCall(url)));

        notifyUrls(item, (res) => {
            resolve(res);
        });

        notifyUrls(item, resolve);

const asyncOperation = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve();
        }, 2000);
    });
};

const asyncOperation = () => new Promise(resolve => setTimeout(resolve, 2000));

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

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { return this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) =>  this.myAsyncCall(url)));

        notifyUrls(item, (res) => {
            resolve(res);
        });

        notifyUrls(item, resolve);

const asyncOperation = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve();
        }, 2000);
    });
};

const asyncOperation = () => new Promise(resolve => setTimeout(resolve, 2000));

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

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { return this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) =>  this.myAsyncCall(url)));

        notifyUrls(item, (res) => {
            resolve(res);
        });

        notifyUrls(item, resolve);

const asyncOperation = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve();
        }, 2000);
    });
};

const asyncOperation = () => new Promise(resolve => setTimeout(resolve, 2000));

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

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { return this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) =>  this.myAsyncCall(url)));

        notifyUrls(item, (res) => {
            resolve(res);
        });

        notifyUrls(item, resolve);

const asyncOperation = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve();
        }, 2000);
    });
};

const asyncOperation = () => new Promise(resolve => setTimeout(resolve, 2000));

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

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { return this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) =>  this.myAsyncCall(url)));

        notifyUrls(item, (res) => {
            resolve(res);
        });

        notifyUrls(item, resolve);

const asyncOperation = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve();
        }, 2000);
    });
};

const asyncOperation = () => new Promise(resolve => setTimeout(resolve, 2000));

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

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { return this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) =>  this.myAsyncCall(url)));

        notifyUrls(item, (res) => {
            resolve(res);
        });

        notifyUrls(item, resolve);

const asyncOperation = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve();
        }, 2000);
    });
};

const asyncOperation = () => new Promise(resolve => setTimeout(resolve, 2000));

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

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { return this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) =>  this.myAsyncCall(url)));

        notifyUrls(item, (res) => {
            resolve(res);
        });

        notifyUrls(item, resolve);

const asyncOperation = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve();
        }, 2000);
    });
};

const asyncOperation = () => new Promise(resolve => setTimeout(resolve, 2000));

Interview question, setTimeout should be called first before console.log

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function callMe(delay) {
  return new Promise((resolve) => {
    setTimeout(() => {
      console.log("Called");
      // Resolve Promise, when Timeout is over
      resolve();
    }, delay);
  });
}

// Async Main Function
(async () => {
  const delays = [500, 1000, 1500];
  for (let delay of delays) {
    // Await the Timeout with the Promise
    await callMe(delay);
  }
  console.log("Completed");
})();

Dynamic number of currying strings

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const func = (arg) => {
  const args = [arg];
  const inner = (arg) => {
    args.push(arg);
    return inner;
  };
  inner.join = () => args.join(':');
  return inner;
};

console.log(func('hello')('world').join(':'));
console.log(func('hello')('world')('today').join(':'));

How type casting works in Python?

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def get():
    prompt = 'Give a number or a word.\n'
    x = input(prompt)
    try:
        float(x)
        print('You entered a number.')

    except:
        print('You entered a string.')

See all related Code Snippets

Community Discussions

Trending Discussions on interview

How it is possible to cast parent to child in c#
How to resolve Custom Sort Runtime error 1004
Trigger a function after 5 API calls return (in a distributed context)
Calculate average of any two numbers in a given array in JavaScript?
Why wasn't this boolean value being registered in Go?
How the server make sure clients requests doesn't interfere with each other?
Why ambiguous reference error while using Left without parameters type?
Counting total number of paper pieces
Permutations of the same 4 digits resulting into 2 pairs
Async operations when instance created

Trending Discussions on interview

QUESTION

How it is possible to cast parent to child in c#

Asked 2021-Jun-15 at 12:54

A few days ago in an interview, i was asked to explain following cases:

public class Parent
{

}
public class Child:Parent
{

}

Case1:

Parent p = new Child();
    var c = (Child)p;

Case2:

    Parent p = new Parent();
    var c = (Child)p;

I said case1 is valid and case2 is invalid , but he asked:

Why case2 is invalid while both p variable in case1 and case2 are Type of Parent class?

In case2 we get runtime exception by following message:

Unable to cast object of type 'Parent' to type 'Child

While in case1 p variable was also type of Parent class.

He wanted me to explain it from point of stack and heap memory.

Have you any idea?

Update:

The very spot that interviewer misguided me was exactly where he said in both cases p is type of 'parent' class, based on the answers, just static types of both variables are 'parent', but in run-time they have different types and it's run-time type that really matters.

ANSWER

Answered 2021-Jun-15 at 12:54

You must make a distinction between the static type of a variable (the type known at compile time) and the run time type of an object reference assigned to a variable.

The static type of p is Parent in both cases because it is declared as Parent p. No matter what you assign it. You may even assign it null.

The run time type of the value of p after the assignment is Child in the first case and Parent in the second case. It would be undetermined if p was null.

It is okay to assign a Child to a Parent, because the Child class derives from Parent. A Child is therefore a Parent (in OO terms).

However, a Parent is not a Child, because it does not derive from it. Therefore, in the second case, you cannot cast p to Child. In the first case the cast is valid, because you cast the object to its actual run time type. It tells the compiler, I know that this object assigned to a Parent variable is a Child, so, please, treat it as a Child. This does not involve any conversion; however, a runtime check will be performed, possibly throwing an exception, if the cast was not allowed.

You were asked to explain it from point of view of stack and heap memory. I'm sorry to say, but this has absolutely nothing to do with stack or heap memory. It has to do with inheritance rules and assignment compatibility.

Of course, here we are dealing with reference types (classes). This allows us to derive Child from Parent. This would not be possible with value types (structs). The point is reference type versus value type, not heap versus stack, which is an implementation detail. And btw., a value type (struct) field in a class will also be stored on the heap.

See also: The Stack Is An Implementation Detail, Part One and Two (Eric Lippert's blog)

You did not ask for it but casting to a derived type is mostly preceded by a type test, because you usually do not know the run time type in advance. Let us say that the Child class adds a new method DriveParentsToDespair() (only children can do this). Then you could use Type testing with pattern matching to test the type and assign it to a new variable at the same time:

if (p is Child child) {
    child.DriveParentsToDespair();
}

This avoids an exception in case p has a run time type of Parent.

Source https://stackoverflow.com/questions/67960172

QUESTION

How to resolve Custom Sort Runtime error 1004

Asked 2021-Jun-15 at 11:03

I'm trying to sort my rows according to the Status (B), according to a custom order. I used to have Status in A, and the code worked fine, but then wanted to add an additional column before it and everything's been scuppered. Now getting a 1004 error.

My table spans A:L. Here's the code:

Sub custom_sort()
    Dim vCustom_Sort As Variant, rr As Long

    vCustom_Sort = Array("Published", "Submitted", "Distributed", "Amending", "Awaiting Sign-off", "Materials Drafting", "Working Up", "Arranging Interview", "Sourcing Information/Images", "Confirmed", "Pitched", "On Hold", "Archive")
    Application.AddCustomList ListArray:=vCustom_Sort

    With ActiveWorkbook.Worksheets("Activity")
        .Sort.SortFields.Clear
        rr = .Cells(.Rows.Count, "B").End(xlUp).Row
        With .Range("A2:L" & rr)
            .Cells.Sort Key1:=.Columns(1), Order1:=xlAscending, DataOption1:=xlSortNormal, _
                        Orientation:=xlTopToBottom, Header:=xlYes, MatchCase:=False, _
                        OrderCustom:=Application.CustomListCount + 1

        End With
        .Sort.SortFields.Clear
    End With

End Sub

Screenshot of spreadsheet reflecting problem described above

ANSWER

Answered 2021-Jun-11 at 21:02

The error implies that it can't find a range to work with. As we are working with a table, the .Columns(2) wont work.

This part hints that you have a table that your are trying to sort.

There's two approaches that I can think of now, to solve this:

1. Sort a regular range by custom list

We can remove the table by:

Click on the table
Go to design tab
Convert to Range

Then your originally code will work (Changed Key1:=.Columns(2)):

Sub custom_sort()
    Dim vCustom_Sort As Variant, rr As Long

    vCustom_Sort = Array("Published", "Submitted", "Distributed", "Amending", "Awaiting Sign-off", "Materials Drafting", "Working Up", "Arranging Interview", "Sourcing Information/Images", "Confirmed", "Pitched", "On Hold", "Archive")
    Application.AddCustomList ListArray:=vCustom_Sort

    With ActiveWorkbook.Worksheets("Activity")
        .Sort.SortFields.Clear
        rr = .Cells(.Rows.Count, "B").End(xlUp).Row
        With .Range("A2:L" & rr)
            .Sort Key1:=.Columns(2), Order1:=xlAscending, DataOption1:=xlSortNormal, _
                        Orientation:=xlTopToBottom, Header:=xlYes, MatchCase:=False, _
                        OrderCustom:=Application.CustomListCount + 1
        End With
        .Sort.SortFields.Clear
    End With
End Sub

1. Sort a table by custom list

We can sort the table, but we need to know the table name + table column we want to sort. We get the table name here (click on the table) and in my example the table name is Table1:

Then we can use this code (I have comment where you need to adjust the names)

Sub custom_sort_table()

Dim ws As Worksheet
Set ws = ActiveSheet
Dim sortcol As Range
Dim tbl As ListObject
Dim vCustom_Sort As Variant

Set tbl = ws.ListObjects("Table1") 'Set/adjust table name
Set sortcol = Range("Table1[Status]") 'Set/adjust table column you want to sort (i.e. table name + column name)

vCustom_Sort = Array("Published", "Submitted", "Distributed", "Amending", "Awaiting Sign-off", "Materials Drafting", "Working Up", "Arranging Interview", "Sourcing Information/Images", "Confirmed", "Pitched", "On Hold", "Archive")
Application.AddCustomList ListArray:=vCustom_Sort

With ActiveWorkbook.Worksheets("Activity")
    With tbl.Sort 'sort table
        .SortFields.Clear 'clear previous sorting
        .SortFields.Add Key:=sortcol, SortOn:=xlSortOnValues, Order:=xlAscending, CustomOrder:=Application.CustomListCount
        .Header = xlYes 'Ignore heading
        .Apply 'Need to apply sorting, otherwise it won't change sort
    End With
End With

End Sub

Source https://stackoverflow.com/questions/67940612

QUESTION

Trigger a function after 5 API calls return (in a distributed context)

Asked 2021-Jun-14 at 00:33

My girlfriend was asked the below question in an interview:

We trigger 5 independent APIs simultaneously. Once they have all completed, we want to trigger a function. How will you design a system to do this?

My girlfriend replied she will use a flag variable, but the interviewer was evidently not happy with it.

So, is there a good way in which this could be handled (in a distributed context)? Note that each of the 5 API calls are made by different servers and the function to be triggered is on a 6th server.

ANSWER

Answered 2021-Jun-13 at 23:34

If I were asked this, my first thought would be to use promises/futures. The idea behind them is that you can execute time-consuming operations asynchronously and they will somehow notify you when they've completed, either successfully or unsuccessfully, typically by calling a callback function. So the first step is to spawn five asynchronous tasks and get five promises.

Then I would join the five promises together, creating a unified promise that represents the five separate tasks. In JavaScript I might call Promise.all(); in Java I would use CompletableFuture.allOf().

I would want to make sure to handle both success and failure. The combined promise should succeed if all of the API calls succeed and fail if any of them fail. If any fail there should be appropriate error handling/reporting. What happens if multiple calls fail? How would a mix of successes and failures be reported? These would be design points to mention, though not necessarily solve during the interview.

Promises and futures typically have modular layering system that would allow edge cases like timeouts to be handled by chaining handlers together. If done right, timeouts could become just another error condition that would be naturally handled by the error handling already in place.

This solution would not require any state to be shared across threads, so I would not have to worry about mutexes or deadlocks or other thread synchronization problems.

She said she would use a flag variable to keep track of the number of API calls have returned.

One thing that makes great interviewees stand out is their ability to anticipate follow-up questions and explain details before they are asked. The best answers are fully fleshed out. They demonstrate that one has thought through one's answer in detail, and they have minimal handwaving.

When I read the above I have a slew of follow-up questions:

How will she know when each API call has returned? Is she waiting for a function call to return, a callback to be called, an event to be fired, or a promise to complete?
How is she causing all of the API calls to be executed concurrently? Is there multithreading, a fork-join pool, multiprocessing, or asynchronous execution?
Flag variables are booleans. Is she really using a flag, or does she mean a counter?
What is the variable tracking and what code is updating it?
What is monitoring the variable, what condition is it checking, and what's it doing when the condition is reached?
If using multithreading, how is she handling synchronization?
How will she handle edge cases such API calls failing, or timing out?

A flag variable might lead to a workable solution or it might lead nowhere. The only way an interviewer will know which it is is if she thinks about and proactively discusses these various questions. Otherwise, the interviewer will have to pepper her with follow-up questions, and will likely lower their evaluation of her.

When I interview people, my mental grades are something like:

S — Solution works and they addressed all issues without prompting.
A — Solution works, follow-up questions answered satisfactorily.
B — Solution works, explained well, but there's a better solution that more experienced devs would find.
C — What they said is okay, but their depth of knowledge is lacking.
F — Their answer is flat out incorrect, or getting them to explain their answer was like pulling teeth.

Source https://stackoverflow.com/questions/67963121

QUESTION

Why wasn't this boolean value being registered in Go?

Asked 2021-Jun-12 at 06:41

I've begun learning Go, and I ran into a strange bug, and an even stranger fix for it working on a HackerRack problem:

func countingValleys(steps int32, path string) int32 {
    // Write your code here
    var level int32 = 0
    var valleys int32 = 0
    // The below declaration was throwing the initial error
    insideValley := false

    for _, char := range path {
        fmt.Println(insideValley)
        if string(char) == "U" {
            if level == -1 {
            insideValley = false
                valleys += 1
            }
            level += 1
        } else if string(char) == "D"{
           if level == 0 {
            insideValley = true
            }
             level -= 1
        }
    }
    return valleys
}

The compiler was complaining that insideValley is declared by not used, both on HR and the Go playground. I added the fmt.Println call immediately inside of the for loop to debug, suspecting it to be a scope error, and the error went away AND my code passed all tests for the challenge, leaving me wondering:

Why was the error being thrown in the first place? My current understanding of variable scope in Go is that when declared in a function like this, it will be available to all blocks contained within the function.
Why did adding the fmt.Println of that var fix the error? I would have assumed with my current understanding that IF you can only nest X amount of blocks before variables in enclosing blocks become out of scope, the only fix for it would involve pointers.

ANSWER

Answered 2021-Jun-12 at 06:41

So we have an actually correct answer here, the issue is that you're writing to the boolean but never reading from it. Without the Println(), it's not used in a conditional or any other expression anywhere that depends on its value, so the assignments to it don't affect the program flow. You could remove all of the lines assigning values to insideValley and the program would act no differently than it does right now (excepting the Println(), of course, which is why adding that "fixed" the issue).

Go is specifically designed to flag "junk" code like that, that adds nothing to the program flow, as a compiler error (well, in most cases. Unused globals and unused functions are some exceptions to that). Simply add in whatever is supposed to be using that boolean's value (such as a conditional based on its value), and you'll stop getting the "variable unused" error.

And as noted in the comments of Vishwa Ratna's answer, vars do not have to be used in every logical pathway. They only need to be used (ie. read from) in at least one logical pathway.

Source https://stackoverflow.com/questions/67944883

QUESTION

Why ambiguous reference error while using Left without parameters type?

Asked 2021-Jun-09 at 13:06

I found "ambiguous reference to overloaded definition" while trying to practice scala interview question.

I was trying to find the outcome of following code block which results in compilation error :

Code :

for {
  v1 <- Left[Int,Int](1)
  v2 <- Right(2)
  v3 <- Right(3)
  v4 <- Left(4)
} yield v1 + v2 + v3 + v4

Error :

<pastie>:17: error: ambiguous reference to overloaded definition,
both method + in class Int of type (x: Char)Int
and  method + in class Int of type (x: Byte)Int
match argument types (Nothing)
} yield v1 + v2 + v3 + v4
                     ^

Why Scala compiler gives ambiguous reference error when we specified type only on v1 field but not on v4 ?

I also tried following version with different parameter type in v1 and v4 and it worked !

for {
  v1 <- Left[String,Int]("1")
  v2 <- Right(2)
  v3 <- Right(3)
  v4 <- Left[Int, Int](4)
} yield v1 + v2 + v3 + v4

And the output is :

res20: scala.util.Either[Any,Int] = Left(1)

I tried with one more version which also resulted into error :

for {
  v1 <- Left(1)
  v2 <- Right(2)
  v3 <- Right(3)
  v4 <- Left(4)
} yield v1 + v2 + v3 + v4

output :

<console>:17: error: value + is not a member of Nothing
       } yield v1 + v2 + v3 + v4

How exactly the for comprehension works here with Left and Right ? Why the first and last case are not working in my example ?

ANSWER

Answered 2021-Jun-09 at 13:06

It's because there's no common inferred types and you didn't specify the types for all the Either.

scala> for (v1 <- Right(2)) yield v1
res13: scala.util.Either[Nothing,Int] = Right(2)

Solution is to give them common types

for {
  v1 <- Left[Int,Int](1)
  v2 <- Right[Int,Int](2)
  v3 <- Right[Int,Int](3)
  v4 <- Left[Int,Int](4)
} yield v1 + v2 + v3 + v4

Which gives Left(1). This result makes sense due to Either being right-biased and for comprehension serving as a flatMap.

According to the documentation: "Either is right-biased, which means that Right is assumed to be the default case to operate on. If it is Left, operations like map, flatMap, ... return the Left value unchanged"
https://www.scala-lang.org/api/2.12.0/scala/util/Either.html

Source https://stackoverflow.com/questions/67888163

QUESTION

Counting total number of paper pieces

Asked 2021-Jun-08 at 11:14

The below is an interview question which I was unable to solve and needs some help.

Question:

A Person is playing with paper and during his game he folds the paper vertically in one turn and then horizontally in another turn and repeats the process n number of times. After he's done he cuts the paper vertically and horizontally. The task at hand is to take a number "N" as input and find the count of paper pieces that will be there after cutting the paper vertically and horizontally after folding it n times following the pattern as mentioned above.

Constraints:

1< N <10^5

N : Total number of turns
As the answer can be very large output the result mod 10^9+7

Test Cases

Input: 0
Output: 4

Input: 1
Output: 6

Input: 2
Output: 9

Input: 3
Output: 15

I tried to find some number pattern but couldn't find any also this question doesn't seem related to any algorithm and thus I was unable to find any proper approach. Please help suggesting some approach.

ANSWER

Answered 2021-Jun-08 at 11:14

As the comments mentions, you should look for a pattern in the sections (4 corners) and not in the total parts. We will enumerate the corners as a vector like this:

(a (top left),b (top Right) ,c (bottom left) ,d (bottom Right))

Also for sake of consistency and understanding we always fold from right to left in the vertical fold (right half on top of the left half) and from bottom to top in the horizontal fold (bottom half on top of the top half) and we start with horizontal as the first fold we will preform.

first we start with 1 in each corner so when we divide we get the sum of all corners like this:

(1,1,1,1) = 1 + 1 + 1 + 1 = 4 (n = 0)

lets see what will happen in each corner after few runs:

(2,1,2,1) = 2 + 1 + 2 + 1 = 6 (n = 1)

(4,2,2,1) = 4 + 2 + 2 + 1 = 9 (n = 2)

(6,3,4,2) = 6 + 3 + 4 + 2 = 15 (n = 3)

(9,6,6,4) = 9 + 6 + 6 + 4 = 25 (n = 4)

maybe at first its hard to see the relation between but actually the pattern is pretty simple:

(a,b,c,d) -> (a+b,a,c+d,c) when you fold vertically (from right to left)

and

(a,b,c,d) -> (a+c,b+d,a,b) when you fold horizontally (from bottom to top)

so you can get the recursive relationship and here some simple code in C for this:

int func(int a, int b, int c, int d, int n) {
 if (n == 0) return (a + b + c + d);
 if (n % 2 == 0) return func(a + b, a, c + d, c, n - 1);
 else return func(a + c, b + d, a, b, n - 1);
}

from here you can get a better computational results but this is a start

Source https://stackoverflow.com/questions/67884018

QUESTION

Permutations of the same 4 digits resulting into 2 pairs

Asked 2021-Jun-07 at 14:06

How do I get the permutations in for below 4 numbers with only 2 results. Expected pair is [4,4] and [4,4]

4,4,4,4
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
xnor  -1  pair is  (4, 4)
Total Pairs 12

Here is the program which I wrote.

from itertools import permutations

userInput = input("Please enter comma separated numbers : \n")

inputArray = [int(e) if e.isdigit() else e for e in userInput.split(',')]

result = permutations(inputArray, 2)
count = 0
for pair in list(result):
    xNor = ~(pair[0] ^ pair[1])
    if xNor == -1:
        print("xnor ", xNor, " pair is ", pair)
        count = count + 1

print("Total Pairs", count)

Modification This is one of the question i was asked during an interview. Appreciate any hint or solution.

ANSWER

Answered 2021-Jun-06 at 18:40

You're actually using a brute-force approach, which is O(n!). Here's a O(n²) approach:

def xnor_pairs(seq):
    # Create two pointers: one on the start and another at the end
    i0 = 0
    i1 = len(seq) - 1
    
    pairs = []
    
    # Repeat this until the start pointer has not reached the end
    while i0 < len(seq) - 1:
        a, b = seq[i0], seq[i1]
        
        # If the start and end indexes are equal
        if i0 == i1:
            # Move the start pointer one position closer to the end
            i0 += 1
            # Move the end pointer back to the end
            i1 = len(seq) - 1
            
            continue

        # If the condition is satisfied (a XNOR b == -1)
        if ~(a ^ b) == -1:
            # Append to the pairs
            pairs.append((a, b))
        
        # Move the end pointer one position closer to the start
        i1 -= 1
        
    return pairs

print(xnor_pairs([1, 2, 3, 3, 4, 4, 4, 10, 10, 10]))
# Output: [(3, 3), (4, 4), (4, 4), (4, 4), (10, 10), (10, 10), (10, 10)]

Source https://stackoverflow.com/questions/67861761

QUESTION

Async operations when instance created

Asked 2021-Jun-07 at 08:06

I had a job interview yesterday, and I was given a coding challenge as the following:

// 3. Coding challenge.
// The goal is to make function1/function2 to work only when the constructor has finished its async operations.
// You CAN'T change the notifyUrls function. Imagine it's a 3th party library you don't have control on.

// CAN'T CHANGE THIS.
//===================
function notifyUrls(item, callback) {
    asyncOperation(item).then((res) => {
        callback(res);
    });
}
//===================

 const asyncOperation = () => { return new Promise((resolve, reject) => { setTimeout(() => { console.log('Timeout execute'); resolve(); }, 2000); }); };

const URL1 = 'http://www.somerestapi/get1';
const URL2 = 'http://www.somerestapi/get2';
const URL3 = 'http://www.somerestapi/get3';

class MyClass {

    constructor() {
        [URL1, URL2, URL3].forEach(item => {
            notifyUrls(item, () => { });
        });
    }

    myFunction1() {
        // Only start working when constructor finished notifying.
        // ...
        console.log('myFunction1');
    }

    myFunction2() {
        // Only start working when constructor finished notifying.
        // ...
        console.log('myFunction2');
    }
}

And here is what I did:

// CAN'T CHANGE THIS.
//===================
function notifyUrls(item, callback) {
    asyncOperation(item).then((res) => {
        callback(res);
    });
}
//===================

 const asyncOperation = () => { return new Promise((resolve, reject) => { setTimeout(() => { console.log('Timeout execute'); resolve(); }, 2000); }); };

const URL1 = 'http://www.somerestapi/get1';
const URL2 = 'http://www.somerestapi/get2';
const URL3 = 'http://www.somerestapi/get3';

class MyClass {

    constructor() {
        this.ready = Promise.all([URL1, URL2, URL3].map((url) => { this.myAsyncCall(url); }));
    }

    myAsyncCall(item) {
        return new Promise((resolve, reject) => {
            notifyUrls(item, (res) => { resolve(res); });
        });
    }

    async myFunction1() {
        if (await this.ready) {
            // Only start working when constructor finished notifying.
            // ...
            console.log('myFunction1');
        }
    }

    myFunction2() {
        // Only start working when constructor finished notifying.
        // ...
        console.log('myFunction2');
    }
}

(async () => {
    const myClass = new MyClass();
    await myClass.myFunction1();
})();

But the output is:

myFunction1
Timeout execute
Timeout execute
Timeout execute

What I want the output to be is:

Timeout execute
Timeout execute
Timeout execute
myFunction1

How can I work around it? Thanks.

ANSWER

Answered 2021-Jun-07 at 08:06

The problem is in

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { this.myAsyncCall(url); }));

Your map callback doesn't return anything

Either do

    this.ready = Promise.all([URL1, URL2, URL3].map((url) => { return this.myAsyncCall(url); }));

    this.ready = Promise.all([URL1, URL2, URL3].map((url) =>  this.myAsyncCall(url)));

Adding some coding tips

        notifyUrls(item, (res) => {
            resolve(res);
        });

Can simply be

        notifyUrls(item, resolve);

and

const asyncOperation = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve();
        }, 2000);
    });
};

is just

const asyncOperation = () => new Promise(resolve => setTimeout(resolve, 2000));

Source https://stackoverflow.com/questions/67867873

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