自己手写

#include<iostream>
#include<stack>
using namespace std;

const int N = 100010;

int n;
int a[N], b[N];
stack<int> s;

int main()
{
    cin >> n;

    for(int i = 1 ; i <= n ; i ++ )
        scanf("%d",&a[i]);

    s.push(a[1]);
    b[1] = -1;
    for (int i = 2 ;i <= n ; i ++ )
    {
        if (a[i] > s.top())
        {
            b[i] = s.top();
            s.push(a[i]);
        }
        else
        {
            while ( !s.empty() && s.top() > a[i] )
            {
                s.pop();
            }
            b[i] = s.empty() ? -1 : s.top();
            s.push(a[i]);
        }
    }

    for ( int i = 1 ; i <= n ; i ++)
        printf("%d ",b[i]);

    return 0;
}