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\n", AC.Search(str) );

    }

    return 0;

}