computer-science | A collection of data-structures and algorithms in Golang | Learning library
kandi X-RAY | computer-science Summary
kandi X-RAY | computer-science Summary
This repository will be a place to practice computer science and crytpography principles in Golang. The following items are going to be examined:.
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Top functions reviewed by kandi - BETA
- ConstructSuffixArray builds a SuffixResult from a string s .
- KMP is similar to KMP
- del deletes node
- output a node
- BbreadthFirstSearch finds the first node in the given graph
- Encode returns the canonical encoding of s .
- Decode decodes base64 encoded string
- InitializeFailureTable initializes the failure table for the needle .
- Power returns the power of x n .
- Merge merges two lists of values .
computer-science Key Features
computer-science Examples and Code Snippets
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Trending Discussions on computer-science
QUESTION
I was recently told that AVL sort is not in place. Can anyone please explain it? From the below code, I am not sure where I assign extra space when sorting. In this code, when a data structure is built or an element are inserted, elements are ordered by their key.
Reference for the claim: They are using this claim to motivate "binary heap"
[1].https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-006-introduction-to-algorithms-spring-2020/lecture-notes/MIT6_006S20_r08.pdf
Reference for code:
...ANSWER
Answered 2021-Dec-09 at 09:25Wikipedia defines an in-place algorithm as follows:
In computer science, an in-place algorithm is an algorithm which transforms input using no auxiliary data structure. However, a small amount of extra storage space is allowed for auxiliary variables. The input is usually overwritten by the output as the algorithm executes. An in-place algorithm updates its input sequence only through replacement or swapping of elements.
So one of the properties of an algorithm that is called "in-place" is that it does not copy all input values into an newly allocated data structure. If an algorithm creates a binary search tree (like AVL), for which node objects are created that are populated with the input values, then it cannot be called in-place by the above definition, even if at the end of the process the values are copied back into the input array.
As a comparison, heap sort does not have to create a new data structure, as the input array can be used to reorganise its values into a heap. It merely has to swap values in that array in order to sort it. It is therefore an in-place algorithm.
QUESTION
Similar to this question on a private forum: Why don’t RegEx implementations support intersection and complement?
Finite automatas built from regular expressions are closed under the set operations union, intersection, complement, and difference. These FA are closed under the two additional operations concatenation and Kleene star.
Anecdotally, concatenation, union, and star operations are ubiquitous in regular expression implementations. Why don't regular expression engines typically support the other set operations intersection, complement, and difference?
An example FA demonstrating the intersection of the two FA substring 01 and odd number of 1s from these lecture notes.
...Scott Aaronson. 6.045J Automata, Computability, and Complexity. Spring 2011. Massachusetts Institute of Technology: MIT OpenCourseWare, https://ocw.mit.edu. License: Creative Commons BY-NC-SA.
ANSWER
Answered 2021-Oct-01 at 09:44Regex engines that support lookarounds let you implement intersection, complement and difference :
(?=pattern1)pattern2will match a string that both pattern1 and pattern2 match(?!pattern).*will match anything that isn't matched by pattern (although more realistically you'd usepatternas a regex and have your higher-level environment reverse the match result)(?!pattern1)pattern2will match a string that is matched by pattern2 but not by pattern1
However lookarounds are a rather recent feature in the history of regular expressions and still aren't supported by many regex engines. Why is that?
I'm not well versed in regex's history, but if I believe a cursory glance at Wikipedia articles, they originate from mathematician Stephen Cole Kleene's definition of regular languages which is only based on the union, concatenation and Kleene star operations, which might explain why those are the basic operations in regular expressions.
QUESTION
I am looking for a solution to the problem from Beginning Microsoft SQL Server® 2008 Programming book.(AdventureWorks database used)
Ques> Show the most recent five orders that were purchased from account numbers that have spent more than $70,000 with AdventureWorks.
I found a solution to this on See query but this is not working. What's the error in this query?
...ANSWER
Answered 2021-Aug-30 at 11:08I'm not entirely sure why you though this query would work:
It's querying for orders where the account number is not in the top 5 which is the opposite of what we want, moreover TOP 5 here has no ordering so it's entirely random. And this is entirely in the wrong place, the question wants the top 5 orders, not the top 5 accounts.
It's also filtering for orders where each of the orders individually has a value greater than 70000. And HAVING SUM(so.LineTotal > 70000) is a syntax error.
I would advise you instead to use window functions here
QUESTION
Hey I'm trying to implement nested drag&drop within re-order sequencesin my MERN app. I working to find ideal approach for mongodb data model and implement to Lexicographic order or linked lists for infinite sub folders. I used Model Tree Structures in this link but every node have limitless children for that require recursion and recursive functions or currying. Documentations not clear enough for make do that.
I want show all tree once and not sohuld appear after than click to arrow icon.There is my doodles for front side generation that working with only one depth such like graph nodes. Maybe Modified Preorder Tree Traversal implementation examples you have for this scenario.
ANSWER
Answered 2021-Aug-21 at 12:38You could create a Map to key your objects by slug. The values per key will be the result objects for parent objects. Include an entry for null, which will collect the top-level elements.
Then iterate the data again to populate children arrays -- when that property does not exist yet, create it on the fly. Finally output the top-level elements.
QUESTION
Tensoflow Embedding Layer (https://www.tensorflow.org/api_docs/python/tf/keras/layers/Embedding) is easy to use, and there are massive articles talking about "how to use" Embedding (https://machinelearningmastery.com/what-are-word-embeddings/, https://www.sciencedirect.com/topics/computer-science/embedding-method) . However, I want to know the Implemention of the very "Embedding Layer" in Tensorflow or Pytorch. Is it a word2vec? Is it a Cbow? Is it a special Dense Layer?
...ANSWER
Answered 2021-Jun-09 at 09:22Structure wise, both Dense layer and Embedding layer are hidden layers with neurons in it. The difference is in the way they operate on the given inputs and weight matrix.
A Dense layer performs operations on the weight matrix given to it by multiplying inputs to it ,adding biases to it and applying activation function to it. Whereas Embedding layer uses the weight matrix as a look-up dictionary.
The Embedding layer is best understood as a dictionary that maps integer indices (which stand for specific words) to dense vectors. It takes integers as input, it looks up these integers in an internal dictionary, and it returns the associated vectors. It’s effectively a dictionary lookup.
QUESTION
I am currently learning python and as a little test a friend of mine gave me a problem from the MIT open courseware python course. However, I am struggling on part C of the problem. It requires that you use a binary search to find the right amount you need to save if you want to buy a house in 3 years given a starting salary.
Here is the problem pdf for further details (scroll to part C): https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and-programming-in-python-fall-2016/assignments/MIT6_0001F16_ps1.pdf
I have technically "solved" it and am able to find the correct value according to the test cases given but the percents have many digits and the amount of bisection searches counted is much higher than that of the test cases.
I was wondering if there is actually anything wrong with my code and if I am implementing the binary search correctly with regards to this problem.
Example test cases: Test Case 1:
Enter the starting salary: 150000
Best savings rate: 0.4411
Steps in bisection search: 12
MY RESULTS:
Enter the starting salary: 150000
Best savings rate: 0.4411391177390328
Steps in bisection search: 40
Thanks for any help!
Apologies in advance for this question I am still learning ;P
My Code:
...ANSWER
Answered 2021-May-25 at 17:24The line which causes too many iterations is
QUESTION
I'm trying to fetch data from a dynamic route. I'm in pages/science-and-engineering/[field].js and I'm using getStaticPath with getStaticProps as usual but for some reason getStaticProps never get executed, and the component never renders. ONLY getStaticPath get executed and everything works fine in there, and then it just stops.
...ANSWER
Answered 2021-May-02 at 12:32The params returned in paths must match your dynamic route path: pages/posts/[name]. You need to replace field with name.
QUESTION
I'm learning Vue and would appreciate help as I can't find an answer on here or the rest of the internet as to why my radio buttons are not working with a v-if statement even though I have bound the model and I can see the value change.
expected results:
the user toggles if they have a degree using the radio buttons, the div with the class "degree-wrapper" would disappear if they select false.
actual result:
the user toggles if they have a degree using the radio buttons, the div with the class "degree-wrapper" does not disappear if they select false.
what I find odd is that I can see the value change and the value is bound? so why isn't the v-if toggling displaying the "degree-wrapper" div when v-model is changing it to false.
here is my code it's written with classes in vue3 and typescript.
...ANSWER
Answered 2021-Apr-20 at 14:21I built a sample component to demonstrate the functionality. Built with Vue 2 using the Vue CLI, but should be applicable to Vue 3.
QUESTION
According to my understanding, for each test sample, kNN classifier algorithm computes the distances between the current test sample and all the training samples and select a certain number of the closest neighbors, and determine the label for the test sample, then next test sample will be done.
My code is similar to the sample kNN classifier code in the following hyperlink which is very simple:
The number of my training samples is 8000, the number of test samples is 1500, the sample dimension is 12.
When I ran the sklearn kNN classifier code, it only took 2 seconds, and the accuracy is good.
I doubted the time spent by sklearn kNN algorithm, so I wrote a simple code to compute the distance between the test sample and all the training samples, and found it is a time-consuming process, even not including the sorting algorithm. The code for distance calculation is as follow:
...ANSWER
Answered 2021-Jan-21 at 08:42You are right, nearest-neighbor search is really time intensive. If you do it naively, you have are at a runtime of O(n^2). Good thing is, that sklearn uses some clever algorithms to circumvent calculating all the distances.
Have a look at the docs and you will see that one parameter is the algorithm used for nearest-neighbor search, e.g. BallTree. These algorithms speed up the calculation a lot.
On another note, your code is a little inefficient. Instead of calculating each dimension by hand, you could do:
QUESTION
Question: Sort the functions in increasing order of big-O complexity
- f1(n) = (n^0.999999) log n
- f2(n) = 10000000n
- f3(n) = 1.0000001^n
- f4(n) = n^2
My answer to this question is that is: 3, 2, 1, 4 (in increasing order) based on the rule that we can ignore constants.
But the answer I found in the solution booklet is:
The correct order of these functions is f1(n), f2(n), f4(n), f3(n).
I am not able to understand this, Can anyone explain? Here is the solution's explanation if it helps.
Thanks in advance!
...ANSWER
Answered 2020-Nov-01 at 17:44The following facts reveal the ordering:
O(n^k) > O(log(n))for anyk > 0.O(k^n) > O(n^b)for anyk > 1.
This might feel counter-intuitive since 1.0000001^n starts off really slow, but we are talking of asymptotic complexity here. The exponential growth, albeit slow in practical scenarios, dominates any polynomial growth as we go towards infinity. And the same is true for polynomial growth being greater than logarithmic growth.
So:
- f3(n), with the exponential growth is of highest complexity.
- f4(n) being greater than f2(n) and f1(n) is quite obvious.
- f1(n) vs f2(n) -- Consider them
n^0.999999 * lognvsn^0.999999 * n^0.000001. So what determines the comparison here islognvsn^0.000001. As we have stated in fact (1), polynomial growth > logarithmic growth. So f2(n) > f1(n).
Combining the results, we have O(f1(n)) < O(f2(n)) < O(f4(n)) < O(f3(n)).
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