QuickSort

#include <bits/stdc++.h>

using namespace std;

ifstream fin("algsort.in");
ofstream fout("algsort.out");

void quicksort(int a[], int st, int dr) {
    if(st < dr) {
        int mid = (st + dr) >> 1;
        swap(a[st], a[mid]);
        int i = st , j = dr, d = 0;
        while(i < j) {
            if(a[i] > a[j]) {
                swap(a[i], a[j]);
                d = !d;
            }
            i += d;
            j -= !d;
        }
        quicksort(a, st , i - 1);
        quicksort(a, i + 1, dr);
    }
}

const int NMAX = 5e5 + 5;
int N, a[NMAX];

int main() {
    fin >> N;
    for(int i = 1; i <= N; ++i)
        fin >> a[i];
    quicksort(a, 1, N);
    for(int i = 1; i <= N; ++i)
        fout << a[i] << ' ';
}