quick sort

quicksort.cpp

/* QUICK SORT */

#include <iostream>
#include <vector>
using namespace std;

void quick(vector<int> a, int n, int beg, int end)
{
        int left, right, loc = beg;
        while(left != right){
        left = beg, right = end;
        while(a[loc]<a[right] && loc!=right)
          right--;
        if(a[loc]>a[right]){
          int temp = a[loc];
          a[loc] = a[right];
          a[right] = a[loc];
        }
        loc = right;
        while(a[loc] > a[left] && loc!=left)
          left++;
        if(a[loc] < a[left]){
          int temp = a[loc];
          a[loc] = a[left];
          a[left] = a[loc];
        }
        loc = left;
        }
        cout << loc;
}
main()
{
        vector<int> val(20), lower(20), upper(20);
        int n, top = 0, beg, end;
        cout <<"enter number of elements ";
        cin >> n;
        cout<<"enter values"<<endl;
        for(int i =1; i<=n; i++){
          cout << i <<": ";
          cin >> val[i];
        }
        if(n>1){
        top++;
        lower[1] = 1;
        upper[1] = n;
        }
        while(top!=0){
        beg = lower[top]; end = upper[top];
        top--;
        int loc = quick(val, n, beg, end);
        //cout << loc;
        if(beg < loc-1){
          top++; lower[top] = beg;
          upper[top] = loc-1;
        }
        if(loc+1 < end){
          top++; lower[top] = loc+1;
          upper[top] = end;
        }
        }
//      for(int j=1; j<=n; j++)
//      cout<<" "<<val[j];
}