Quicksort

#include<stdio.h>
#include<stdlib.h>
#include<iostream>
#include<algorithm>
#define N 1000000

using namespace std;

int a
;

void quicksort(int x[], int left, int right)
{
if(left >= right)return;
int i = left;
int j = right;
swap(x[i], x[(rand() % (right - left + 1)) + left]);
int key = x[i];
while(i < j){
while(i < j && x[j] >= key)j--;
if(i < j)swap(x[i++], x[j]);
while(i < j && x[i] <= key)i++;
if(i < j)swap(x[i], x[j--]);
}
quicksort(x, left, i - 1);
quicksort(x, i + 1, right);
}

int main()
{
int n;
while(~scanf("%d", &n)){
for(int i = 0; i < n; i++){
cin >> a[i];
}
quicksort(a, 0, n - 1);
for(int i = 0; i < n; i++){
cout << a[i] << ' ';
}
cout << endl;
}
return 0;
}