Quick Sort

quick_sort.cpp

#include <bits/stdc++.h>
using namespace std;
void quicksort(int[],int,int);
int partition(int[],int,int);
// Input and Main Function
int main()
{
    int a[30],p,n,r;
    cout<<"enter the number of element";
    cin>>n;
    cout<<"enter the element :";
    for(int i=0; i<n; i++)
    {
        cin>>a[i];
    }
    // Call of initial function
    quicksort(a,0,n-1);
    cout<<"\n Array after sorting";
    for(int i=0; i<n; i++)
    {
        cout << a[i] << " ";
    }
    return 0;
}
    void quicksort(int a[], int p, int r)
    {
        if(p<r)
        {
            //Partition of element
            int q;
            q=partition(a, p, r);
            quicksort(a,p,q);
            quicksort(a,q+1,r);
        }
    }
    int partition(int a[], int p, int r)
    {
        int i,j,pivot,temp;
        pivot=a[p];
        i=p;
        j=r;
        while(1)
        {
            /*
            i -> will keep on traversing the list,
            j -> we will keep on traverse the list from back
            */
            while(a[i] < pivot && a[i] != pivot)
                i++;
            while(a[j] > pivot && a[j] != pivot)
                j--;
            if(i<j)
            {
                /*
                Store the sorted value in file and return to temp
                */
                temp = a[i];
                a[i] = a[j];
                a[j] = temp;
            }
            else
            {
                return j;
            }
        }
    }