Non-Recursive Quick Sort

import java.util.*;

import java.util.Stack;

class QuickSortNonRec

{

    static void Display(int x[], int n)

    {

        int i;

        System.out.println(" ");

        for(i=0;i<n;i++)

            System.out.print("\t"+x[i]+ " ");

        System.out.println(" ");

    }

    static int Partition(int x[], int lb, int ub )

    {

        int a, down, temp, up,pj;

        a=x[lb];

        up=ub;

        down=lb;

        while(down<up)

        {

            while(x[down]<=a && down<up)

                down=down+1;       

            while(x[up]>a)

                up=up-1;         

            if(down<up)

            {

                temp=x[down]; 

                x[down]=x[up];

                x[up]=temp;

            }

        }

        x[lb]=x[up];

        x[up]=a;

        pj=up;

        return (pj);

    }

    static void Quick(int[] a, int lb, int ub)

    {

        Stack S = new Stack();

        S.push(lb);

        S.push(ub);

        while (!S.empty())

        {

            ub = (Integer)S.pop();

            lb = (Integer)S.pop();

            if (ub <= lb) continue;

            int i = Partition(a, lb, ub);

            if (i-lb > ub-i)

            {

                S.push(lb);

                S.push(i-1);

            }

            S.push(i+1);

            S.push(ub);

            if (ub-i >= i-lb)

            {

                S.push(lb);

                S.push(i-1);

            }

        }

    }

    public static void main(String args[ ])

    {

        int i,n=10;

        int x[]=new int[10];

        Scanner in = new Scanner(System.in);

        System.out.println("Enter 10 numbers");

        for(i=0;i<n;i++)

            x[i] = in.nextInt();

        Quick(x,0,n-1);

        System.out.println("\nSorted Elements are :");

        for(i=0;i<n;i++)

            System.out.print(x[i] + "  ");

    }

}