题解 | 查找 |set.upper_bound

#include<bits/stdc++.h>
using namespace std;
int main(){
	set<int>s;
	//write your code here......
	int n, m, a, x;
	cin>>n>>m;
	for(int i=0; i<n; i++){
		cin>>a;
		s.insert(a);
	}
	for(int i=0; i<m; i++){
		cin>>x;
		auto it = s.upper_bound(x);
		if(it!=s.end()){
			cout<<*it<<endl;
		}else{
			cout<<-1<<endl;
		}

	}
	return 0;
}