题目链接：单调栈

#include <iostream>

using namespace std;

const int N = 100010;

int n;
int stk[N], tt;

int main()
{
    cin >> n;
    for(int i = 0; i < n; i ++)
    {
        int x;
        cin >> x;
        while(tt && stk[tt] >= x) tt--;
        if(tt) cout << stk[tt] << ' ';
        else cout << "-1" << ' ';
        stk[++tt] = x;
    }
    return 0;
}