P3808 【模板】AC自动机（简单版）

题面

https://www.luogu.org/problem/P3808

题解

#include<bits/stdc++.h>
#define N 500010
using namespace std;
queue<int> q;
struct acmato{
  int c[N][26],val[N],fail[N],cnt;
  void insert(char *s) {
    int len=strlen(s); int now=0;
    for (int i=0;i<len;i++) {
      int v=s[i]-'a';
      if (!c[now][v]) c[now][v]=++cnt;
      now=c[now][v];
    }
    val[now]++;
  }
  void build() {
    for (int i=0;i<26;i++) if (c[0][i]) fail[c[0][i]]=0,q.push(c[0][i]);
    while (!q.empty()) {
      int u=q.front(); q.pop();
      for (int i=0;i<26;i++) if (c[u][i]) fail[c[u][i]]=c[fail[u]][i],q.push(c[u][i]);
      else c[u][i]=c[fail[u]][i];
    }
  }
  int query(char *s){
    int len=strlen(s); int now=0,ans=0;
    for (int i=0;i<len;i++) {
      now=c[now][s[i]-'a'];
      for (int t=now;t&&val[t]>0;t=fail[t]) ans+=val[t],val[t]=-1;
    }
    return ans;
  }
} AC;
int n;
char p[1000005];
int main(){
  scanf("%d",&n);
  for (int i=1;i<=n;i++) scanf("%s",p),AC.insert(p);
  AC.build();
  scanf("%s",p);
  int ans=AC.query(p);
  cout<<ans<<endl; 
  return 0;
}