Quick_Sort.cpp

#include<bits/stdc++.h>
using namespace std;

int partition(int *a, int start, int end){

    int pivot=a[end];
    //P-index indicates the pivot value index
    
    int P_index=start;
    int i,t; //t is temporary variable
    
    //Here We will check if array value is less than pivot
    //Then we will place it at left side by swapping 
    
    for(i=start;i<end;i++){
    	if(a[i]<=pivot){
            t=a[i];
            a[i]=a[P_index];
            a[P_index]=t;
            P_index++;
        }
    }

    //Now exchanging value of
    //pivot and P-index
    t=a[end];
    a[end]=a[P_index];
    a[P_index]=t;
    
    //at last returning the pivot value index
    return P_index;
}

void Quicksort(int *a, int start, int end){

    if(start<end){
        int P_index = partition(a,start,end);
        Quicksort(a,start,P_index-1);
        Quicksort(a,P_index+1,end);
    }
}

int main(){

    int n;
    cout<<"Enter number of elements : ";
    cin>>n;

    int a[n];
    cout<<"Enter the array elements :\n";
    for(int i=0;i<n;i++)
    {
        cin>>a[i];
    }

    Quicksort(a,0,n-1);

    cout<<"After Quick Sort the array is :\n";
    for(int i=0;i<n;i++)
    {
        cout<<a[i]<<" ";
    }
    
    return 0;
}