求助

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll mod = 1e9 + 7;
const int N = 5000005;
const int INF = 0x3f3f3f3f;
int trie[N][30], tot, p[N], f[N];
void insert(char *ch) {
    int u = 0, len = strlen(ch + 1);
    for (int i = 1; i <= len; i++) {
        int x = ch[i] - 'a';
        if (!trie[u][x]) {
            trie[u][x] = ++tot;
        }
        u = trie[u][x];
    }
    p[u] = 1;
}
int find(char *ch, int l, int r) {
    int u = 0, ans = 0;
    for (int i = l; i <= r; i++) {
        int x = ch[i] - 'a';
        if (!trie[u][x]) {
            return 0;
        }
        u = trie[u][x];
        if (p[u]) {
            f[i] = 1;
        }
    }
    return p[u];
}
char ch[N];
int main() {
    int n, m;
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i++) {
        scanf("%s", ch + 1);
        insert(ch);
    }
    f[0] = 1;
    for (int i = 1; i <= m; i++) {
        scanf("%s", ch + 1);
        int len = strlen(ch + 1), u = 1;
        for (int j = 1; j <= len; j++) {
            f[j] = 0;
        }
        for (int j = 0; j <= len; j++) {
            if (f[j]) {
                find(ch, j + 1, len);
            }
        }
        for (int j = len; j >= 0; j--) {
            if (f[j]) {
                printf("%d\n", j);
                break;
            }
        }
    }
    return 0;
}