1. Program for Quick Sort

   #include<stdio.h> 
   #include<conio.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]; // pivot
       int i = (low - 1); // Index of smaller element
       int j;
       for (j = low; j <= high- 1; j++)
       {
           // If current element is smaller than or
           // equal to pivot
           if (arr[j] <= pivot)
           {
               i++; // increment index of smaller element
               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);
       }
   }
   void printArray(int arr[], int size)
   {
       int i;
       for (i=0; i < size; i++)
           printf("%d ", arr[i]);
       printf("\n");
   }
   void main()
   {
       int arr[] = {4, 7, 8, 9, 1, 5};
       int n = sizeof(arr)/sizeof(arr[0]);
       clrscr();
       printf("Unsorted array: \n");
       printArray(arr, n);
       quickSort(arr, 0, n-1);
       printf("\nSorted array: \n");
       printArray(arr, n);
       getch();
   }
   

2. Step by Step Example for Quick Sort a. Consider the unsorted values {25, 13, 7, 34, 56, 23, 13, 96, 14, 2} with first element as pivot element i.e 25 is pivot

b. Hence after quick sort the sorted array becomes 2, 07, 13, 13, 14, 23, 25, 34, 56, 96