C Program for Merge Sort
// C program for Merge Sort
#include <stdio.h>
#include <stdlib.h>
// Merges two subarrays of arr[].
// First subarray is arr[l..m]
// Second subarray is arr[m+1..r]
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]
// Initial index of the first subarray
i = 0;
// Initial index of the second subarray
j = 0;
// Initial index of merged subarray
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++;
}
}
// l is for the 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)
{
// Same as (l+r)/2, but avoids
// overflow for large l and h
int m = l + (r - l) / 2;
// Sort first and second halves
mergeSort(arr, l, m);
mergeSort(arr, m + 1, r);
merge(arr, l, m, r);
}
}
// UTILITY FUNCTIONS
// 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 code
int main()
{
int arr[] = {12, 11, 10, 13, 5, 6, 7, 9, 8};
int arr_size = sizeof(arr) / sizeof(arr[0]);
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 10 13 5 6 7 9 8
Sorted array is
5 6 7 8 9 10 11 12 13
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