好像还算简单(?
Aho-Corasick automaton 多模匹配显然需要建字典树
fail 指针就是找最长的后缀，使它能继续在字典树上匹配
如果叶子节点下一个节点还要往上连边
P3808 AC 自动机（简单版）
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define debug(x) cout<<#x<<" = "<<x<<endl;
const int N = 1e6 + 5;
int n, trie[N][26], num, cnt[N], fail[N];
string s;
inline ll read(){ll s=0,f=1;char c=getchar();while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}while(c>='0'&&c<='9'){s=(s<<1)+(s<<3)+(c^48);c=getchar();}return s*f;
}
void insert(string s){int p = 0;for(int i=0;i<s.size();i++){int c = s[i] - 'a';if(!trie[p][c]) trie[p][c] = ++num;p = trie[p][c];}cnt[p]++;
}
void pretreat(){queue<int> q;for(int i=0;i<26;i++)if(trie[0][i])q.push(trie[0][i]);while(!q.empty()){int h = q.front();q.pop();for(int i=0;i<26;i++){if(trie[h][i]){fail[trie[h][i]] = trie[fail[h]][i];q.push(trie[h][i]);}else trie[h][i] = trie[fail[h]][i];}}
}
int main(){n = read();for(int i=1;i<=n;i++){cin >> s;insert(s);}pretreat();cin >> s;int p = 0, ans = 0;for(int i=0;i<s.size();i++){int c = s[i] - 'a';p = trie[p][c];for(int t = p;t && ~cnt[t];t = fail[t])ans += cnt[t], cnt[t] = -1;}cout << ans;return 0;
}