Questions tagged [mergesort]

Merge sort is an O(n log n) comparison-based sorting algorithm.

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4answers
83 views

MergeSort in Javascript

I implemented the following mergesort algorithm in JavaScript, but I want to know your opinion about if is possible to do better than this. ...
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0answers
40 views

Vector of numbers where merge sort is slow

I'm starting to study sorting algorithms in Python. Merge Sort has a complexity at best and worst cases \$\mathcal{O}(n\log{}n)\$, I want generation a list where Merge Sort is slow but I would some ...
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4answers
183 views

C-based hash matching cracker

How can I improve this hash matching program using either abstraction or search/sort algorithms? We briefly were introduced to searching methods such as bubble sort and merge sort, but I'm not sure ...
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1answer
48 views

What are the downsides of my Mergesort implementation?

Could I ask you to evaluate my implementation of mergesort? I think that it's consistent with \$\mathcal{O}(n \log n)\$ complexity but has a downside that I create a new ...
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2answers
73 views

Merge sorted lists

I want to write a function that merges two sorted lists in Python 3. For example: >> merge_lists([2, 5, 9], [1, 6, 8, 10]) [1, 2, 5, 6, 8, 9, 10] My ...
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Parallel merge sort with thread- and bufferpooling

I did wrote this parallel merge sort with no external dependencies. I tried to make use of modern C++ as much as possible. Can you please tell me how it is? ...
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2answers
129 views

Merge Sort C++11 C++17

Question Any way I can optimize this further using new C++11 or C++17 features? Would also like feedback on my variable naming, memory management, and style (notice my placement of ...
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2answers
505 views

C++ parallel merge sort

I'm a first year computer engineering student who's learning about algorithms and data structures. I've implemented a parallel merge sort algorithm in C++ and would like constructive criticism. This ...
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0answers
45 views

Sorts (merge, quick, bubble) in Python

I'm new to python, and I wrote the following code. Please review, critique and enhance. This project compares quicksort, mergesort and bubblesort write/test the partition routine for ...
3
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1answer
25 views

Python merge sort for a list containing distinct values

This code below is what I think should be the implementation of merge sort in Python and it works as expected. It sorts the given list, where we can safely assume that all values are distinct. But ...
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1answer
248 views

External polyphase merge sort

For comparison with other external sorting algorithms, I have implemented external polyphase merge sort, purported to be useful to sort large files that do not fit into main memory. More theoretical ...
3
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1answer
117 views

Adaptive Merge Sort in C++

As the title says, I'm trying to implement a merge sort algorithm in C++ that's also adaptive. This is a personal exercise, and I don't have any specific application in mind. My main goal is to ...
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0answers
193 views

Linked-list natural merge sort in Python

I implemented the linked-list natural merge sort in Python, and I refered to this awesome if not poetic gist and this implementation in Go. Here is my code: ...
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MergeSort linked list implementation

I wrote a MergeSort implementation of doubly linked list, based on the MergeSort implementation of array on the textbook Algorithms 4th, which is definitely \$O(n \log n)\$. I think my linked list ...
4
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1answer
169 views

Natural merge: mergesort that uses already sorted subarrays

The code bellow is my implementation for the natural merge exercise in Robert Sedgwick's Algorithms book: Write a version of bottom-up mergesort that takes advantage of order in the array by ...
2
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1answer
75 views

Merge sort implementation with various improvements

So I was working on merge sort today, and was trying to speed it up. I would like your opinion on the implementation and if it's possible to make it faster. Besides that I was wondering if there are ...
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0answers
35 views

Implementation of merge sort that takes sublinear extra space

I implemented an algorithm that takes only sublinear extra space as required in the exercise description: Develop a merge implementation that reduces the extra space requirement to max(M, N/M). (...
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2answers
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Python merge sort

In Algorithms Fourth Edition by Robert Sedgewick and Kevin Wayne, the exercise 2.2.10 states that: Implement a version of merge() that copies the second half of a[] to aux[] in decreasing order ...
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1answer
90 views

Merge sort approach in Python

I'm working my way through a book on algorithms. One of the first challenges is the merge sort. I've seen this implemented before, but as the book suggested I coded one from just the method without ...
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2answers
121 views

Merge Sort code in C

Below is the code of Merge Sort for sorting an integer array in ascending order of values written by me. By looking at the code, I am thinking I can make the code more compact and secure, but not ...
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3answers
1k views

C++ code to sort a list of elements

This is a code uses mergesort algorithm to sort a list of elements.What are the possible improvements on the code?Also are there any unhealthy coding practice involved in this code? ...
3
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1answer
323 views

Merge sort Java implementation for an interview

I just learned Merge sort, and I really like this Merge sort implementation since it is very logical and very easy to follow. If I was asked in an interview to implement merge sort, will this ...
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2answers
128 views

Move friendly merge sort - follow-up

This is a follow up to this question. I'm only interested to see if this is implemented correctly for move-only types. ...
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3answers
1k views

Merge Sort implemented using iterators

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2answers
275 views

Merge two sorted lists in Python

Merge two sorted lists ...
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2answers
230 views

Bottom up merge sort in Haskell

Although this sort works on Int lists < length million, when the stack overflows, the last clause of the merge function definition looks odd to me, recursing in 2 places. Is there clearer way to ...
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0answers
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Mergesort in Python optimization

I am currently writing mergesort in Python and have implemented it to work. I have noticed, though, that it is very slow compared to the standard sorted() method. I understand it will always be faster ...
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2answers
149 views

Writing Merge Sort in C++

I am learning programming online and currently watching CS50 lectures, in third lecture, professor introduces us to merge_sort though only through pseudo code, so I wanted someone to review my ...
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3answers
359 views

Using mergesort to sort lexicographically

The program should (and does) the following (paraphrased assignment): There is a catalogue with a list of motorcycles. They have a - Name (spaceless string of 20 chars) - Price (int < 99 ...
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2answers
310 views

Mergesort linked list in C++

My teacher gave us an exercise. We have to sort as quickly as possible. The fastest one gets a reward. On my own system, I am sorting 125000 words within 1.2 seconds. On my teacher's system that is 0....
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1answer
418 views

Recursive merge-sort inversion count algorithm very slow

I am trying to implement a recursive count of inversions in a list of integers by using merge sort and counting the number of split inversions on each recursion. My code works but runs painfully ...
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1answer
129 views

merge_sort and unit testing

I made a merge sort and wanted to ask for code review. It passed all of the unit testing. The idea behind the classic Mergesort algorithm is to divide an array in half, sort each half, and merge the ...
5
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1answer
344 views

Multi-threaded in-place Mergesort on Java

What is an efficient way to implement the Mergesort algorithm in Java such that it meets the following criteria: Must be multi-threaded. Must retain the Mergesort time complexities. Must be in-place ...
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1answer
80 views

Merge Sort Cleanup

I am re-learning my fundamental algorithms, and have been told my Python is overly verbose. Can you take a look at my merge sort algorithm and let me know how you would clean it up and make it more ...
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2answers
70 views

Mergesort, instrumented for counting reads and writes

I have just finished an implementation of mergesort, and I was wondering if I can further reduce the amount of reads and writes. I have looked at it for a while, and to my eyes, I cannot see anything ...
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2answers
1k views

MergeSort in Rust

I've just started learning Rust and put together this working MergeSort implementation. Wondering what I've overlooked and what I could improve. I couldn't figure out a cleaner way to deal with the <...
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1answer
407 views

Mergesort implementation, eliminating slice()

I am having trouble coming up an alternate solution to my mergesort. I think using slice is an expensive operation. I have two implementations, recursive and iterative. ...
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1answer
403 views

Merge Sort efficiency in Python

I am writing a script that takes in many sorted .dat files. I have included sample data but the dataset is quite large. The desired outcome is to have one file with an alphabetically sorted list of ...
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1answer
173 views

C++11 merge sort implementation

I've tried implementing merge sort in C++ just by looking at this Wikipedia graphic. Comparing my code to other merge sort code implementations, it doesn't look quite the same at first glance. Have I ...
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2answers
746 views

Merge sort a given list in Python

Problem: Implement merge sort in python. Don’t use Python’s built in sort or sorted. Assume your inputs will be sufficient for the memory you have. How should I make this code better? ...
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2answers
346 views

Generic Merge Sort in C++

I wanted to implement merge sort in a generic way. I was not sure whether I should use the iterator or the container for the template type. I did not find a way to infer the container type using ...
2
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1answer
40 views

C - non-recursive mergesort on lists

Continuing my foray into classic structures and algorithms, I've tried to implement merge sort for doubly-linked lists. From my (limited) testing it seems the thing I've concocted works, but several ...
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2answers
484 views

Bottom-up singly linked list merge sort in C++

This is an implementation of a singly linked list merge sort I did on paper during a job interview recently, using a bottom-up approach. The requirement was simply "implement a merge sort for a ...
4
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1answer
145 views

Recursive Ruby merge sort

I have implemented a merge sort in Ruby. (Yes, I know, there's Array#sort) I would like to get feedback on code quality and optimization. ...
2
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1answer
352 views

MergeSort implementation in Python

I wanted to share a bit about how to implement your merge sort. Merge sort is a divide and conquer algorithm that breaks down an array into smaller pieces and eventually pieces them back together one ...
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1answer
279 views

Merge sort implementation in C++

I was wondering if this implementation of merge sort could be improved. Are there any things that I have done wrong? ...
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1answer
667 views

Merge two sorted lists

There are many if-else conditions in my code Question 1: I am looking for suggestions to minimize if else conditions. Also, Code in Step 1 and Step2 is almost ...
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1answer
66 views

MergeSort - Is this actually MergeSort?

Will this code actually work as MergeSort? This is working to sort the array but is it MergeSort? My faculty did approve of this but he probably did not see the code properly and I need some serious ...
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4answers
948 views

Generic merge sort in C++ using a user-defined comparison function or the < operator by default

I wanted to implement a generic merge sort algorithm using the same interface as std::sort(). The interface takes first and last iterators to a range of elements in ...
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1answer
117 views

Adaptive Mergesort in Java - follow-up

(See the previous and first iteration.) Adaptive Mergesort This algorithm is from a paper "Sublinear Merging and Natural Mergesort" by Svante Carlsson, Christos Levcopoulos and Ola Petersson. It ...