字典树基础，朴素字符串查找

空间（o(n*m)）

#include<bits/stdc++.h>
using namespace std;
​
const int N = 2e6 + 9;
int nex[N][26];
int cnt[N];
int idx = 2;
void insert(char s[]){int x = 1;for (int i = 0; s[i]; i++){//判断x是否存在是s[i]if (!nex[x][s[i] - 'a'])nex[x][s[i] - 'a'] = idx++;x = nex[x][s[i] - 'a'];}cnt[x]++;
}
bool check(char s[]){int x = 1;for (int i = 0; s[i]; i++)x = nex[x][s[i] - 'a'];return x!=0;
}
​
​
int main(){ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);int n, m; cin >> n >> m;for (int i = 1; i <= n; i++){char s[N]; cin >> s;insert(s);}for (int i = 1; i <= m; i ++ ){char s[N]; cin >> s;cout << (check(s) ? "Y" : "N") << "\n";}return 0;
}