# Merge Sort Program in C

Merge sort is a sorting technique based on divide and conquer technique. With the worst-case time complexity being Ο(n log n), it is one of the most respected algorithms.

## Implementation in C

We shall see the implementation of merge sort in C programming language here −

```#include <stdio.h>

#define max 10

int a[11] = { 10, 14, 19, 26, 27, 31, 33, 35, 42, 44, 0 };
int b[10];

void merging(int low, int mid, int high) {
int l1, l2, i;

for(l1 = low, l2 = mid + 1, i = low; l1 <= mid && l2 <= high; i++) {
if(a[l1] <= a[l2])
b[i] = a[l1++];
else
b[i] = a[l2++];
}

while(l1 <= mid)
b[i++] = a[l1++];

while(l2 <= high)
b[i++] = a[l2++];

for(i = low; i <= high; i++)
a[i] = b[i];
}

void sort(int low, int high) {
int mid;

if(low < high) {
mid = (low + high) / 2;
sort(low, mid);
sort(mid+1, high);
merging(low, mid, high);
} else {
return;
}
}

int main() {
int i;

printf("List before sorting\n");

for(i = 0; i <= max; i++)
printf("%d ", a[i]);

sort(0, max);

printf("\nList after sorting\n");

for(i = 0; i <= max; i++)
printf("%d ", a[i]);
}
```

If we compile and run the above program, it will produce the following result −

## Output

```List before sorting
10 14 19 26 27 31 33 35 42 44 0
List after sorting
0 10 14 19 26 27 31 33 35 42 44
```
merge_sort_algorithm.htm