Practical 3
Aim - : Write a program to sort a array by using merge and quick sort in c language.
Quick Sort
#include <stdio.h>
void swap(int* a, int* b) {
int t = *a;
*a = *b;
*b = t;
int partition(int arr[], int low, int high) {
int pivot = arr[high];
int i = (low - 1);
for (int j = low; j <= high - 1; j++) {
if (arr[j] < pivot) {
i++;
swap(&arr[i], &arr[j]);
swap(&arr[i + 1], &arr[high]);
return (i + 1);
void quickSort(int arr[], int low, int high) {
if (low < high) {
int pi = partition(arr, low, high);
quickSort(arr, low, pi - 1);
quickSort(arr, pi + 1, high);
int main() {
int arr[] = {10, 7, 8, 9, 1, 5};
int n = sizeof(arr) / sizeof(arr[0]);
quickSort(arr, 0, n - 1);
printf("Sorted array: ");
for (int i = 0; i < n; i++)
{ printf("%d ", arr[i]);
return 0;
Output of quick sort -:
Merge Sort -:
#include <stdio.h>
#include <stdlib.h>
void merge(int arr[], int l, int m, int r)
{ int i, j, k;
int n1 = m - l + 1;
int n2 = r - m;
int L[n1], R[n2];
for (i = 0; i < n1; i++)
L[i] = arr[l + i];
for (j = 0; j < n2; j++)
R[j] = arr[m + 1 + j];
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++;
while (i < n1) {
arr[k] = L[i];
i++;
k++;
while (j < n2) {
arr[k] = R[j];
j++;
k++;
}
void mergeSort(int arr[], int l, int r) {
if (l < r) {
int m = l + (r - l) / 2;
mergeSort(arr, l, m);
mergeSort(arr, m + 1, r);
merge(arr, l, m, r);
int main() {
int arr[] = {12, 11, 13, 5, 6, 7};
int arr_size = sizeof(arr) / sizeof(arr[0]);
printf("Given array is \n");
for (int i = 0; i < arr_size; i++)
printf("%d ", arr[i]);
printf("\n");
mergeSort(arr, 0, arr_size - 1);
printf("\nSorted array is \n");
for (int i = 0; i < arr_size; i++)
printf("%d ", arr[i]);
return 0;
Output for Merge sort -:
