AC自动机-HDU2222-模板题

http://acm.hdu.edu.cn/showproblem.php?pid=2222

一个AC自动机的模板题。用的kuangbin的模板，静态建Trie树。可能遇到MLE的情况要转动态建树。

 

AC自动机的讲解看这里

http://blog.csdn.net/niushuai666/article/details/7002823

http://blog.csdn.net/mobius_strip/article/details/22549517

/*--------------------------------------------------------------------------------------*/
//        Helica's header 
//        Second Editions
//        2015.11.7
//
#include <algorithm>
#include <iostream>
#include <cstring>
#include <ctype.h>
#include <cstdlib>
#include <cstdio>
#include <vector>
#include <string>
#include <queue>
#include <stack>
#include <cmath>
#include <set>
#include <map>

//debug function for a N*M array 
#define debug_map(N,M,G) printf("\n");for(int i=0;i<(N);i++)\
{for(int j=0;j<(M);j++){\
printf("%d",G[i][j]);}printf("\n");}                
//debug function for int,float,double,etc.
#define debug_var(X) cout<<#X"="<<X<<endl;
/*--------------------------------------------------------------------------------------*/
using namespace std;

int N,M,T;

struct Trie
{
    int next[500010][26],fail[500010],end[500010];
    int root,L;
    int newnode()
    {
        for(int i=0;i<26;i++) next[L][i] = -1;
        end[L++] = 0;
        return L-1;
    }
    void init()
    {
        L = 0;
        root = newnode();
    }

    void insert(char *s)
    {
        int len = strlen(s);
        int now = root;
        for(int i=0;i<len;i++)
        {
            if(next[now][s[i]-'a'] == -1)
                next[now][s[i]-'a'] = newnode();
            now = next[now][s[i]-'a'];
        }
        end[now]++;
    }

    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 now = Q.front();
            Q.pop();
            for(int i=0;i<26;i++)
            {
                if(next[now][i] == -1)
                    next[now][i] = next[fail[now]][i];
                else
                {
                    fail[next[now][i]] = next[fail[now]][i];
                    Q.push(next[now][i]);
                }
            }
        }

    }

    int query(char *s)
    {
        int len = strlen(s);
        int now = root;
        int ans = 0;
        for(int i=0;i<len;i++)
        {
            now = next[now][s[i]-'a'];
            int temp = now;
            while(temp != root)
            {
                ans += end[temp];
                end[temp] = 0;
                temp = fail[temp];
            }
        }
        return ans;
    }
    void debug()
    {
        for(int i=0;i<L;i++)
        {
            printf("id = %3d,fail = %3d,end = %3d,chi = [",i,fail[i],end[i]);
            for(int j=0;j<26;j++)
                printf("%2d",next[i][j]);
            printf("]\n");
        }
    }
};

char buf[1000100];
Trie ac;

int main()
{
    scanf("%d",&T);
    while(T--)
    {
        ac.init();
        scanf("%d",&N);
        for(int i=0;i<N;i++)
        {
            scanf("%s",buf);
            ac.insert(buf);
        }
        ac.build();
        //ac.debug();
        scanf("%s",buf);
        printf("%d\n",ac.query(buf));
    }
}

 

 

第N次入门AC自动机。。。成功。。。