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Added merge-sort in MATLAB (#27783)

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* Added merge-sort in MATLAB

* fix: changed c++ to cpp
This commit is contained in:
Mahmud031
2019-06-25 05:02:26 +03:00
committed by Randell Dawson
parent 787729c910
commit 57d66ef6df
1 changed files with 81 additions and 10 deletions
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91
guide/english/algorithms/sorting-algorithms/merge-sort/index.md
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@ -8,7 +8,7 @@ Merge Sort is a <a href='https://guide.freecodecamp.org/algorithms/divide-and-co
Since this is a recursion based algorithm, we have a recurrence relation for it. A recurrence relation is simply a way of representing a problem in terms of its subproblems.
```
T(n) = 2 * T(n / 2) + O(n)
T(n) = 2 * T(n / 2) + O(n)
```
Putting it in plain english, we break down the subproblem into two parts at every step and we have some linear amount of work that we have to do for merging the two sorted halves together at each step.
@ -52,15 +52,6 @@ If right > l:
* <a href='https://www.cs.usfca.edu/~galles/visualization/ComparisonSort.html'>USFCA</a>
* <a href='https://www.hackerearth.com/practice/algorithms/sorting/merge-sort/visualize/'>HackerEarth</a>
### Relavant videos on freeCodeCamp YouTube channel
* <a href='https://youtu.be/TzeBrDU-JaY'>Merge Sort algorithm - MyCodeSchool</a>
### Other Resources:
* <a href='https://en.wikipedia.org/wiki/Merge_sort' target='_blank' rel='nofollow'>Wikipedia</a>
* <a href='www.geeksforgeeks.org/merge-sort' target='_blank' rel='nofollow'>GeeksForGeeks</a>
* <a href='https://youtu.be/sWtYJv_YXbo' target='_blank' rel='nofollow'>Merge Sort - CS50</a>
### Implementaion in JS
```js
const list = [23, 4, 42, 15, 16, 8, 3]
@ -181,6 +172,32 @@ int main()
```
### Implementation in C++
Let us consider array A = {2,5,7,8,9,12,13}
and array B = {3,5,6,9,15} and we want array C to be in ascending order as well.
```cpp
void mergesort(int A[],int size_a,int B[],int size_b,int C[])
{
int token_a,token_b,token_c;
for(token_a=0, token_b=0, token_c=0; token_a<size_a && token_b<size_b; )
{
if(A[token_a]<=B[token_b])
C[token_c++]=A[token_a++];
else
C[token_c++]=B[token_b++];
}
if(token_a<size_a)
{
while(token_a<size_a)
C[token_c++]=A[token_a++];
}
else
{
while(token_b<size_b)
C[token_c++]=B[token_b++];
}
```cpp
void merge(int arr[], int l, int m, int r)
@ -391,3 +408,57 @@ public class mergesort {
}
}
```
### Implementaion in MATLAB
```matlab
a = [9,4,7,3,8,5,1,6,2];
[sorted] = mergeSort(a);
function [sorted] = mergeSort(unsorted)
len = length(unsorted);
if len == 1
sorted = unsorted;
return;
end
mid = ceil((len)/2);
left = mergeSort(unsorted(1:mid));
right = mergeSort(unsorted(mid+1:end));
sorted = mergeLR(left, right);
end
function [sorted] = mergeLR(left, right)
sorted = [left right]; % add two splited array together
j = 1; % index for 'sorted'
k = 1; % index for 'left'
for i = 1:1:length(right)
% going through every element of the 'right'
if right(i) < left(k)
sorted(j) = right(i); % move the 'right' element before
sorted(j+1:(j+length(left(k:end)))) = left(k:end); % shift the left elemts
j = j+1;
else
while (k <= length(left)) && (right(i) > left(k))
k = k+1;
j = j+1;
end
sorted(j) = right(i);
sorted(j+1:(j+length(left(k:end)))) = left(k:end);
j = j+1;
end
end
end
```
### Relavant videos on freeCodeCamp YouTube channel
* <a href='https://youtu.be/TzeBrDU-JaY'>Merge Sort algorithm - MyCodeSchool</a>
### Other Resources:
* <a href='https://en.wikipedia.org/wiki/Merge_sort' target='_blank' rel='nofollow'>Wikipedia</a>
* <a href='www.geeksforgeeks.org/merge-sort' target='_blank' rel='nofollow'>GeeksForGeeks</a>
* <a href='https://youtu.be/sWtYJv_YXbo' target='_blank' rel='nofollow'>Merge Sort - CS50</a>