HDU 2222 Keywords Search AC自动机

标签：hdu   ac自动机   

题目大意：给出一些单词，和一个句子，问有多少个单词在句子中出现过。

思路：来签到吧

CODE：

#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define P(a) ((a) - 'a')
#define MAX 60
#define _MAX 1000010
using namespace std;

char s[_MAX];

struct Trie{
    Trie *son[26],*fail;
    int cnt;
    
    Trie() {
        memset(son,NULL,sizeof(son));
        fail = NULL;
        cnt = 0;
    }
    void Insert(char *s) {
        Trie *now = this;
        while(*s != '\0') {
            if(now->son[P(*s)] == NULL)
                now->son[P(*s)] = new Trie();
            now = now->son[P(*s)];
            ++s;
        }
        ++now->cnt;
    }
}*root;

struct AC_Automaton{
    
    void Build(int cnt) {
        static char s[MAX];
        for(int i = 1; i <= cnt; ++i) {
            scanf("%s",s);
            root->Insert(s);
        }
        static queue<Trie *> q;
        while(!q.empty()) q.pop();
        for(int i = 0; i < 26; ++i)
            if(root->son[i] != NULL)
                root->son[i]->fail = root,q.push(root->son[i]);
        while(!q.empty()) {
            Trie *now = q.front(); q.pop();
            for(int i = 0; i < 26; ++i)
                if(now->son[i] != NULL) {
                    Trie *temp = now->fail;
                    while(temp != root && temp->son[i] == NULL)
                        temp = temp->fail;
                    if(temp->son[i] != NULL)    temp = temp->son[i];
                    now->son[i]->fail = temp;
                    q.push(now->son[i]);
                }
        }
    }
    int Ask(char *s) {
        int re = 0;
        Trie *now = root;
        while(*s != '\0') {
            while(now != root && now->son[P(*s)] == NULL)
                now = now->fail;
            if(now->son[P(*s)] != NULL)
                now = now->son[P(*s)];
            for(Trie *temp = now; temp != root; temp = temp->fail)
                re += temp->cnt,temp->cnt = 0;
            ++s;
        }
        return re;
    }
}solver;

int cases,cnt;

int main()
{
    for(cin >> cases; cases--;) {
        root = new Trie();
        scanf("%d",&cnt);
        solver.Build(cnt);
        scanf("%s",s);
        printf("%d\n",solver.Ask(s));
    }
    return 0;
}

HDU 2222 Keywords Search AC自动机

标签：hdu   ac自动机   

原文地址：http://blog.csdn.net/jiangyuze831/article/details/41520479