HDU 2222 Keywords Search (AC自动机模板题)

一组数据：

1

3

sss

sss

sss

sss

ans：3

#include <cstdio>
#include <cstdlib>
#include <vector>
#include <algorithm>
#include <cstring>

using namespace std;

//MAX_NODE = StringNumber * StringLength
const int MAX_NODE = 10100 * 50;
//节点个数,一般字符形式的题26个
const int CHILD_NUM = 26;
const int MAXN = 1000100;

struct ACAutomaton {
    //每个节点的儿子,即当前节点的状态转移
    int chd[MAX_NODE][CHILD_NUM];
    //记录题目给的关键数据
    int val[MAX_NODE];
    //传说中的fail指针
    int fail[MAX_NODE];
    //队列,用于广度优先计算fail指针
    int Q[MAX_NODE];
    //字母对应的ID
    int ID[128];
    //已使用节点个数
    int sz;

    //初始化,计算字母对应的儿子ID,如:'a'->0 ... 'z'->25
    void Initialize() {
        fail[0] = 0;
        for (int i = 0 ; i < CHILD_NUM ; i ++) {
            ID[i+'a'] = i;
        }
    }
    //重新建树需先Reset
    void Reset() {
        memset(chd[0] , 0 , sizeof(chd[0]));
        memset( val, 0, sizeof(val) );
        sz = 1;
    }
    //将权值为key的字符串a插入到trie中
    void Insert(char *a, int key) {
        int p = 0;
        for ( ; *a ; a ++) {
            int c = ID[(int)(*a)];
            if (!chd[p][c]) {
                memset(chd[sz] , 0 , sizeof(chd[sz]));
                val[sz] = 0;
                chd[p][c] = sz ++;
            }
            p = chd[p][c];
        }
        val[p] += key;
    }
    //建立AC自动机,确定每个节点的权值以及状态转移
    void Construct() {
        int *s = Q , *e = Q;
        for (int i = 0 ; i < CHILD_NUM ; i ++) {
            if (chd[0][i]) {
                fail[ chd[0][i] ] = 0;
                *e ++ = chd[0][i];
            }
        }
        while (s != e) {
            int u = *s++;
            for (int i = 0 ; i < CHILD_NUM ; i ++) {
                int &v = chd[u][i];
                if (v) {
                    *e ++ = v;
                    fail[v] = chd[ fail[u] ][i];
                    //以下一行代码要根据题目所给val的含义来写
                    //val[v] |= val[ fail[v] ];
                } else {
                    v = chd[ fail[u] ][i];
                }
            }
        }
    }

    int Search( char *str )
    {
        int ans = 0;
        int i = 0;
        int p = 0;
        while ( str[i] )
        {
            int c = ID[ (int)(str[i]) ];
            while ( p != 0 && !chd[p][c] ) p = fail[p];
            if ( chd[p][c] ) p = chd[p][c];
            else p = 0;

            int tmp = p;
            while( tmp != 0 && val[tmp] != 0 )
            {
                ans += val[tmp];
                val[tmp] = 0;
                tmp = fail[tmp];
            }
            ++i;
        }
        return ans;
    }
}AC;

int N;
char str[MAXN];

int main()
{
    AC.Initialize();
    int T;
    scanf( "%d", &T );
    while ( T-- )
    {
        char tmp[60];
        scanf( "%d", &N );
        AC.Reset();
        for ( int i = 0; i < N; ++i )
        {
            scanf( "%s", tmp );
            AC.Insert( tmp, 1 );
        }
        AC.Construct();
        scanf( "%s", str );
        printf( "%d
", AC.Search(str) );
    }
    return 0;
}