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C Program for Iterative Merge Sort
• Last Updated : 06 Dec, 2018

Following is a typical recursive implementation of Merge Sort that uses last element as pivot.

 `/* Recursive C program for merge sort */``#include ``#include `` ` `/* Function to merge the two haves arr[l..m] and arr[m+1..r] of array arr[] */``void` `merge(``int` `arr[], ``int` `l, ``int` `m, ``int` `r);`` ` `/* l is for left index and r is right index of the sub-array``  ``of arr to be sorted */``void` `mergeSort(``int` `arr[], ``int` `l, ``int` `r)``{``    ``if` `(l < r) {``        ``int` `m = l + (r - l) / 2; ``// Same as (l+r)/2 but avoids overflow for large l & h``        ``mergeSort(arr, l, m);``        ``mergeSort(arr, m + 1, r);``        ``merge(arr, l, m, r);``    ``}``}`` ` `/* Function to merge the two haves arr[l..m] and arr[m+1..r] of array arr[] */``void` `merge(``int` `arr[], ``int` `l, ``int` `m, ``int` `r)``{``    ``int` `i, j, k;``    ``int` `n1 = m - l + 1;``    ``int` `n2 = r - m;`` ` `    ``/* create temp arrays */``    ``int` `L[n1], R[n2];`` ` `    ``/* Copy data to temp arrays L[] and R[] */``    ``for` `(i = 0; i < n1; i++)``        ``L[i] = arr[l + i];``    ``for` `(j = 0; j < n2; j++)``        ``R[j] = arr[m + 1 + j];`` ` `    ``/* Merge the temp arrays back into arr[l..r]*/``    ``i = 0;``    ``j = 0;``    ``k = l;``    ``while` `(i < n1 && j < n2) {``        ``if` `(L[i] <= R[j]) {``            ``arr[k] = L[i];``            ``i++;``        ``}``        ``else` `{``            ``arr[k] = R[j];``            ``j++;``        ``}``        ``k++;``    ``}`` ` `    ``/* Copy the remaining elements of L[], if there are any */``    ``while` `(i < n1) {``        ``arr[k] = L[i];``        ``i++;``        ``k++;``    ``}`` ` `    ``/* Copy the remaining elements of R[], if there are any */``    ``while` `(j < n2) {``        ``arr[k] = R[j];``        ``j++;``        ``k++;``    ``}``}`` ` `/* Function to print an array */``void` `printArray(``int` `A[], ``int` `size)``{``    ``int` `i;``    ``for` `(i = 0; i < size; i++)``        ``printf``(``"%d "``, A[i]);``    ``printf``(``"\n"``);``}`` ` `/* Driver program to test above functions */``int` `main()``{``    ``int` `arr[] = { 12, 11, 13, 5, 6, 7 };``    ``int` `arr_size = ``sizeof``(arr) / ``sizeof``(arr);`` ` `    ``printf``(``"Given array is \n"``);``    ``printArray(arr, arr_size);`` ` `    ``mergeSort(arr, 0, arr_size - 1);`` ` `    ``printf``(``"\nSorted array is \n"``);``    ``printArray(arr, arr_size);``    ``return` `0;``}`
Output:
```Given array is
12 11 13 5 6 7

Sorted array is
5 6 7 11 12 13
```

Please refer complete article on Iterative Merge Sort for more details!

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