快速排序

#include <bits/stdc++.h>
using namespace std;
int n;
int a[1000000+5];
void quickly_sort(int l, int r)
{
	if(l>=r)//排序完成，停止 
		return;
	int mid = (l+r)/2;
	swap(a[l],a[mid]);
	int key = a[l];
	int L = l, R = r;
	while(L<R)
	{	
		while(R>L&&a[R]>=key)
			R--;
		a[L]=a[R];
		while(L<R&&a[L]<=key)
			L++;
		a[R]=a[L];
	}
	a[L] = key;
	quickly_sort(l,L-1);
	quickly_sort(R+1,r);
}
int main()
{
    cin>>n;
    for(int i=1;i<=n;i++)
    	cin>>a[i];
    quickly_sort(1,n);
    for(int i=1;i<=n;i++)
		cout<<a[i]<<" ";
    return 0;
}