que15.c

#include <stdio.h>
#include <stdlib.h>

// Function prototypes
void mergeSort(int *arr, int left, int right);
void merge(int *arr, int left, int mid, int right);

int main() {
    int n, i;
    int *arr;

    printf("Enter the number of elements: ");
    scanf("%d", &n);

    arr = (int *)calloc(n, sizeof(int));
    if (arr == NULL) {
        printf("Memory allocation failed!\n");
        return 1;
    }

    printf("Enter the elements:\n");
    for (i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }

    mergeSort(arr, 0, n - 1);

    printf("Sorted array:\n");
    for (i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");

    free(arr);
    return 0;
}

// Merge Sort function
void mergeSort(int *arr, int left, int right) {
    if (left < right) {
        int mid = left + (right - left) / 2;
        mergeSort(arr, left, mid);
        mergeSort(arr, mid + 1, right);
        merge(arr, left, mid, right);
    }
}

// Merge function
void merge(int *arr, int left, int mid, int right) {
    int n1 = mid - left + 1;
    int n2 = right - mid;
    int *L = (int *)calloc(n1, sizeof(int));
    int *R = (int *)calloc(n2, sizeof(int));
    int i, j, k;

    for (i = 0; i < n1; i++) L[i] = arr[left + i];
    for (j = 0; j < n2; j++) R[j] = arr[mid + 1 + j];

    i = 0;
    j = 0;
    k = left;
    while (i < n1 && j < n2) {
        if (L[i] <= R[j]) arr[k++] = L[i++];
        else arr[k++] = R[j++];
    }

    while (i < n1) arr[k++] = L[i++];
    while (j < n2) arr[k++] = R[j++];

    free(L);
    free(R);
}