quicksort.cpp

#include <bits/stdc++.h>  
  
using namespace std;  
int partition (int a[], int start, int end)  
{  
    int pivot = a[end]; 
    int i = (start - 1);  
  
    for (int j = start; j <= end - 1; j++)  
    {  
        if (a[j] < pivot)  
        {  
            i++; 
            int t = a[i];  
            a[i] = a[j];  
            a[j] = t;  
        }  
    }  
    int t = a[i+1];  
    a[i+1] = a[end];  
    a[end] = t;  
    return (i + 1);  
}  
    
void quick(int a[], int start, int end) 
{  
    if (start < end)  
    {  
        int p = partition(a, start, end);  
        quick(a, start, p - 1);  
        quick(a, p + 1, end);  
    }  
}  
  
void printArr(int a[], int n)  
{  
    int i;  
    for (i = 0; i < n; i++)  
        cout<<a[i]<< " ";  
}  
int main()  
{  
    int a[] = { 23, 8, 28, 13, 18, 26 };  
    int n = sizeof(a) / sizeof(a[0]);  
    cout<<"Elements before sorting \n";  
    printArr(a, n);  
    quick(a, 0, n - 1);  
    cout<<"\nElements after sorting \n";    
    printArr(a, n);  
      
    return 0;  
}