y总写法

#include<iostream>

using namespace std;

const int N = 100010;

int n;
int stk[N], tt;

int main()
{
    cin >> n;

    for(int i = 1 ; i <= n ; i ++ )
    {
        int x;
        scanf("%d",&x);
        while ( tt && stk[tt] >= x ) tt--;
        if(tt) printf("%d ",stk[tt]);
        else printf("-1 ");
        stk[++tt] = x;
    }
    return 0;
}