二分查找（lower_bound函数）

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


int main() {
    int n, m, f = 0;
    cin >> n;
    int a[100];
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }
    sort(a,a+n);//排序，不排序查找会失败（二分查找只能查找线性表）
    cin >> m;
    for (int i = 0; i < m; ++i) {
        int target;
        cin >> target;
        int position = lower_bound(a, a + n, target) - a;//lower_bound返回的地址要减去数组的初始地址
        if (position != n && a[position] == target) {
            std::cout << "YES" << std::endl;
        } else {
            std::cout << "NO" << std::endl;
        }
    }
    return 0;
}