题解 | 查找 利用map（红黑树），unordered_map(哈希表)

#include <iostream>
#include<algorithm>
#include<vector>
#include<map>
#include<string>
using namespace std;//find(beginit,endit,x);
int serch2(vector<int> &v, int l, int r, int x) {
	if (l > r) return -1;
	int m = l + (r - l) / 2; 
	if (x == v[m]) {
		return m;
	}
	else if (x < v[m]) return serch2(v, l, m-1, x);
	else return serch2(v, m+1, r, x);
}
int main() {
	int n;
	while (cin >> n) {
		vector<int >v1;
		vector<int>::iterator it;
		int a;
		for (int i = 0; i < n; i++) {
			cin >> a;
			v1.push_back(a);
		}
		map<int, int> findmap;
		for (int i = 0; i < n; i++) {
			findmap.insert({ v1[i],i });

		}
		int m;
		cin >> m;
		for (int i = 0; i < m; i++) {
			int x;
			cin >> x;
			if (findmap.find(x) == findmap.end())cout << "NO" << endl;
			else cout << "YES" << endl;
		}
	}

}