Merge.c

#include <stdio.h>
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; // Initial index of first subarray
    j = 0; // Initial index of second subarray
    k = l; // Initial index of merged subarray
    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++;
    }
    while (j < n2) {
        arr[k] = R[j];
        j++;
        k++;
    }
}
/* 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)
{
    int m;
    if (l < r) {
        m = l + (r - l) / 2;
        mergeSort(arr, l, m);
        mergeSort(arr, m + 1, r);
        merge(arr, l, m, r);
    }
}
void printArray(int A[], int n)
{
    int i;
    for (i = 0; i < n; i++)
        printf("%d ", A[i]);
    printf("\n");
}
/* Driver code */
int main()
{
    int arr[100], n, i;
    printf("\nEnter the number of elements:");
    scanf("%d", &n);
    printf("\nEnter the %d elements\n", n);
    for(i=0; i<n; i++)
        scanf("%d", &arr[i]);
    printf("*******Given array is ******** \n");
    printArray(arr, n);
    mergeSort(arr, 0, n - 1);
    printf("\n******Sorted array is ******\n");
    printArray(arr, n);
    return 0;
}