HDU 2222 模板题

题目  意思 就是说给你N个单词 问模式串里面含有多少个单词；
方法  AC 自动机  首先建立好自动机；然后在构建 fail 指针的时候标记一下路径；然后用模式串去匹配的过程中，不要重复匹配；走过的路程就标记，然后就是简单的计数了；  AC自动机解决多字符匹配问题时候；很好用；
#include<iostream>
#include<stdio.h>
#include<cstring>
#include<algorithm>
using namespace std;

struct date
{
    date *next[27],*fail;
    bool flag;
    int sum;
}tree[512345],*que[512345],*root;
int tail,head,ptr;

date *creat_node( )
{
    for( int i = 0; i <= 26; i++ )
    tree[ptr].next[i] = NULL;
    tree[ptr].fail = NULL;
    tree[ptr].flag = false;
    tree[ptr].sum = 0;
    return &tree[ptr++];
}

void inint( )
{
    tail = head = ptr = 0;
    root = creat_node( );
}

void insert( char *word )
{
    date *temp = root;
    while( *word )
    {
        int num = *word - 'a';
        if( temp->next[num] == NULL )
            temp->next[num] = creat_node( );
            temp = temp->next[num];
        word++;
    }
    temp->sum++;
}

void build_AC( )
{
    que[tail++] = root;
    while( tail > head )
    {
        date *temp = que[head++];
        for( int i = 0; i < 26; i++ )
        if( temp->next[i] != NULL )
        {
            if( temp == root ) temp->next[i]->fail = root;
            else     temp->next[i]->fail = temp->fail->next[i];
            temp->next[i]->flag = true;
            que[tail++] = temp->next[i];
        }
        else
        {
            if( temp == root ) temp->next[i] = root;
            else               temp->next[i] = temp->fail->next[i];
        }
    }
}

int search( char *word ,int ans )
{
    date *temp = root,*p;
    while( *word )
    {
        int num = *word - 'a';
        temp = temp->next[num];
        p = temp;
        while( p != root )
        {
            if( p->flag )
            {
               ans += p->sum;
               p->flag = false;
            }
            else break;
            p = p->fail;
        }
        word++;
    }
    return ans;
}

int main( )
{
    char str[55],cha[1123456];
    int T,i,j,N;
    scanf("%d",&T);
    while( T-- )
    {
        scanf("%d",&N);
        inint( );
        for( i = 1; i <= N; i++ )
        {
            scanf("%s",&str);
            insert( str );
        }
        build_AC( );
        scanf("%s",cha);
        printf("%d\n",search( cha,0 ) );
    }
    return 0;
}