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

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Recurrent merge sort (without recursion)

For educational purpose I implement recurrent merge sort without recursion. The algorithm idea seems absolutely clear but my implementation appears to be really slow: 5 seconds to sort 10,000 ...
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Mergesorting a stack in Java - a new algorithm

(See the previous iteration.) Now I have implemented a stack merge sort that does not have to reverse every substack after sorting it, and it allocates the two auxiliary stacks only once prior to the ...
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63 views

Mergesorting a stack in Java

(See the next iteration.) I have this small program for sorting a stack using mergesort. Basically, the aim was to use as little aid from JDK library as possible. See what I have: ...
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55 views

How to make doubly linked list design more efficient?

I have played recently and implemented doubly linked list with merge sort algorithm. I was wondering if there is any way of improving the algorithm further to make it as fast as possible (I know about ...
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Java merge sort implementation

Is this a good implementation? ...
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Creating a count inversion array of an unsorted array of unique integers

Given an array: arr = [2,3,1,4] I could write a count inversion array such that counting all numbers n2 after a certain ...
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1answer
52 views

Merge sort implementation efficiency

I made a merge sort implementation in C++, which I have tested with the values: 6, 38, 27, 7, 12, 58, 92, 43, 3, 9, 82, 10 producing the correct output of: ...
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Parallel merge sort in Java

I have rolled my own parallel merge sort. My performance figures are as follows: Seed: 1457521330571 java.util.Arrays.sort() in 6840 ms. Sorted: true java.util.Arrays.parallelSort() 3777 ms. ...
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106 views

Natural merge sort in C

I have this C implementation of the natural merge sort: ...
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110 views

Slow merge sort

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Implementation of merge sort in Python

I was working on an assignment and I was hoping to know if the merge sort algorithm I wrote in Python was not making any unnecessary computations. ...
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Implementation of mergesort in C

I have implemented mergesort in C. Any advice on making it more compact? My merge function seems less than fully optimal. ...
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170 views

String merge sort in Java

This snippet is about sorting a set of strings using merge sort. However, this version is tailored for strings as it relies on lcp values: Given two strings \$A\$ ...
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Counting inversions in C++ via mergesort and vectors [closed]

I have a text file that contains 100,000 numbers from 1 ~ 100,000 in an unsorted manner (no duplicates). The name of the file is "IntegerArray.txt" My task is to count the number of inversions in ...
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1answer
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Constructing an odd-even mergesort sorting network

I was searching for a non-recursive odd-even mergesort implementation and found this one: Sedgewick R. The resulting sorting network is not an odd-even-merge sort network. When one draws a diagram ...
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49 views

Natural merge sort in Java - follow-up 3

(See the previous iteration.) Now I have optimized my natural merge sort: Suppose the input sequence is $$\langle 2, 1, 4, 3, 6, 5, \dots, n, n - 1 \rangle.$$ My previous iterations would degrade ...
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Merge two sorted linked lists without recursion

Is this an effective way for merging two lists? It seemed too long. struct Node { int item; Node *next; }; Method: ...
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1answer
58 views

Merge sort in Clojure

I made my own version of merge sort: ...
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3answers
99 views

Mergesort performance in C

I have two questions about my code: Are there any performance improvements in this implementation or generally (register int ?) that I could make? What could I ...
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1answer
118 views

Mergesort in C++

I'm flexing the C++ muscle and came up with the following implementation of Mergesort. Any suggestions as to the implementation and style are welcome. ...
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Run-aware merge sort

The concept is very, very simple: let's do merging run by run (a run is a range without decrement). ...
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Parallel Merge Sort in Scala

I have been trying to implement parallel merge sort in Scala. My current implementation is about as fast as .sorted, but I have no idea what would be the right ...
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Merge two list and discarding duplicates

I am trying to implement a function that merges two ordered lists into a third (ordered) one, but duplicates have to be discarded (basically the last step of a mergesort). I think that this code can ...
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C++ implementation of merge sort

I am studying the merge sort algorithm and implemented it. In the mergeSort function, I am allocating two new vectors. Can I do it without allocating extra memory? ...
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1answer
113 views

Merge Sort - Using Ruby and Recursion

I am implementing the algorithms of Course: Coursera Algorithm I. I implemented the Merge-Sort using recursion and although it sorts correctly I am not sure if it is a correct implementation of this ...
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Natural merge sort in Java - follow-up 2

See the the previous iteration. Now I refactored the code a bit so that I do not need to pass like 6 parameters to helper methods. Also, I did a small tweak that allows the sort to arrive to the ...
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2answers
348 views

Bottom up mergesort in C++

See the next iteration. I have this C++ implementation of bottom-up mergesort (mergesort using iteration instead of recursion): bottom_up_mergesort.h: ...
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Takes in two sorted lists and outputs a sorted list that is their union

Write a function that takes in two sorted lists and outputs a sorted list that is their union Could anyone help me to improve this code and make it more user-friendly? We are not supposed to ...
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Merge Sort without pointers in C

As part of an online course exercise, I was supposed to implement Merge Sort in C. Pointers were still not discussed prior to this exercise, so I have to work with arrays. Memory efficiency is not ...
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1answer
56 views

Another Scheme Mergesort

Here's a merge sort I wrote trying to learn Scheme. ...
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1answer
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Sorting a linked list using mergesort

This sorts a linked list using mergegort. Can you please critique my code and provide your thoughts on where I should improve my code? ...
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1answer
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Bottom up mergesort - singly linked list

I have written the following program in Go to mergesort a singly linked list. It does bottom up merge sort and hence does not have to find the mid of the linked list. Please review the algorithm and ...
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Mergesort through recursion

Could someone kindly have a look at the recursive merge sort below and let me know if there are any improvements? I'm mainly interested in either improving the code speed or making the code shorter. ...
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1answer
223 views

Counting number of inversions

This is a HackerEarth Challenge Problem. Question: Puchi hates to carry luggage, but unfortunately he got a job to carry the luggage of his N friends in office. Each day, one of his N ...
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1answer
200 views

Bottom up mergesort in Java

See the next iteration. I have this iterative mergesort (a.k.a. bottom-up mergesort). BottomUpMergesort.java: ...
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898 views

The stocks problem - find the biggest profit that can be made

The Stocks Problem: Given an array of n integers representing the price of a stock over the course of n days, determine the maximum profit you can make if you can buy and sell exactly 1 stock ...
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Beginner implementation of Merge Sort

This is my first time implementing a merge sort (just getting started with algorithms & data structures). Are there any obvious things I have done wrong? I am also worried that I have overused ...
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Merge Sort in Perl

I'm new to Perl and have successfully written a merge sort program. I'll paste the entire program below, but would like mostly a review of the subroutines ...
5
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1answer
324 views

Merge sort implementation in JS

Just for learning and practicing I've created a completely recursive version of the merge sort algorithm. I've tested it a little bit and it seems working, but I'm quite sure that it can be largely ...
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202 views

Merge Sort algorithm

I just read and experimented with C++ implementation of the merge sort algorithm from the Wikipedia page. During the experiments I have slightly modified the source code and would like to know how ...
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Merging sorted arrays

I'd like to know if it's ok to write like this or there is a better, prettier way to do this. The merging itself is ok. I'm more interested in dealing with the situation when one of the arrays is ...
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Modern, C++ compliant, merge sort

This is a kind of follow up to my previous sort implementation review with specific questions to merge sort, and Modern C++ idioms. ...
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1answer
389 views

Natural mergesort

This is a problem from Robert Sedgwick's Algorithms book: Write a version of bottom-up mergesort that takes advantage of order in the array by proceeding as follows each time it needs to find two ...
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1answer
185 views

Fast merge sort in JavaScript

When developing a user interface that allows sorting by various different fields, I noticed that Array.prototype.sort() is extremely slow for large inputs. After ...
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Parallel natural merge sort

Continuing working on Natural merge sort, I have parallelized it. Requires \$\Theta(N)\$ space and runs in $$\Omega(N + \frac{N}{P}) \cap \mathcal{O}(N + \frac{N}{P}\log_2\frac{N}{P})$$ time, where ...
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1answer
102 views

Natural merge sort - follow-up

The previous iteration at Natural merge sort Now my code relies on C++14 and looks like: natural_merge_sort.h: ...
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461 views

Natural merge sort

Note: the next iteration at Natural merge sort - follow-up I have compiled natural merge sort algorithm from Java to C++. Natural merge sort sacrifices at most \$2N\$ amount of work in order to ...
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1answer
106 views

Mergesort using map-reduce, multithreads, buffers and condition variables

I wrote a map reduce program which uses multi threads, bounded buffers, condition variables. It works perfectly for some types of inputs. In the program there are N mappers, R reducers, 1 merger. ...
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Merge sort implementation: sorting feels clunky

I got bored and decided to make a merge sort from scratch. I like everything, except for my "merging" of the two arrays into a sorted array inside the for loop. I ...