AC自动机板子（from. qwer）

Posted 2020-08-29 Soda

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <iostream>
#include <string>
#include <queue>
using namespace std;
const int N=510000;
struct Tri
{
    int Next[N][26], fail[N], val[N], root, L;
    void init() {L = 0;root = newnode();}
    int newnode()
    {
        for(int i = 0;i < 26;i++) Next[L][i] = -1;
        val[L++] = 0;
        return L - 1;
    }

    void insert(char s[])
    {
        int len = strlen(s), cur = root;
        for(int i = 0;i < len;i++)
        {
            if(Next[cur][s[i]-‘a‘] == -1)
                Next[cur][s[i]-‘a‘] = newnode();
            cur = Next[cur][s[i]-‘a‘];
        }
        val[cur]++;
    }
    void build()
    {
        queue<int>Q;
        fail[root] = root;
        for(int i = 0;i < 26;i++)
            if(Next[root][i] == -1) Next[root][i] = root;
            else
            {
                fail[Next[root][i]] = root;
                Q.push(Next[root][i]);
            }
        while(!Q.empty())
        {
            int cur = Q.front(); Q.pop();
            for(int i = 0;i < 26;i++)
                if(Next[cur][i] == -1)
                    Next[cur][i] = Next[fail[cur]][i];
                else
                {
                    fail[Next[cur][i]]=Next[fail[cur]][i];
                    Q.push(Next[cur][i]);
                }
        }
    }
    int query(char s[])
    {
        int len = strlen(s), cur = root, res = 0;
        for(int i = 0;i < len;i++)
        {
            cur = Next[cur][s[i]-‘a‘];
            int tmp = cur;
            while (tmp != root)
            {
                res += val[tmp];
                val[tmp] = 0;
                tmp = fail[tmp];
            }
        }
        return res;
    }
};
char s[N];
Tri AC;
int n;
int main()
{
      scanf("%d",&n);
      AC.init();
      for(int i = 0;i < n;i++)
      {
          scanf("%s",s);
          AC.insert(s);
      }
      AC.build();
      scanf("%s",s);
      printf("%d\n",AC.query(s));
      return 0;
}