#include<bits/stdc++.h>
using namespace std;

const int N = 3e6 + 5;
int stk[N];
int t = -1;
int f[N];
int index[N];


int main(){
	int n;
	cin >> n;
	for(int i = 1; i <= n; i++){
		int x;
		scanf("%d", &x);
		while(t > -1 && stk[t] < x){
			f[index[t] - 1] = i;
			t--;
		}
		t++;
		stk[t] = x;
		index[t] = i;
	}
	for(int i = 0; i < n; i++){
		printf("%d ", f[i]);
	}
	return 0;
}

为什么这段代码交上去编译失败，而把头文件改成<iostream>就编译成功了