785. 快速排序

#include <iostream>
using namespace std;

const int N = 1e5 + 10;

int n;
int q[N];

void quick_sort(int q[], int l, int r)
{
    if (l >= r) return ;
    
    int i = l - 1, j = r + 1, x = q[l + r >> 1];
    while (i < j)
    {
        while (q[++ i] < x);
        while (q[-- j] > x);
        if (i < j)  swap(q[i], q[j]);
    }
    
    quick_sort(q, l, j);
    quick_sort(q, j + 1, r);
}

int main()
{
    cin >> n;
    for (int i = 0; i < n; ++ i)    cin >> q[i];
    
    quick_sort(q, 0, n - 1);
    
    for (int i = 0; i < n; ++ i)    cout << q[i] << " ";
    
    return 0;
}