Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 67122    Accepted Submission(s): 22584
#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <vector>
#include <iomanip>
#include <math.h>
#include <map>
using namespace std;
#define FIN     freopen("input.txt","r",stdin);
#define FOUT    freopen("output.txt","w",stdout);
#define INFLL   0x3f3f3f3f3f3f3f
#define lson    l,m,rt<<1
#define rson    m+1,r,rt<<1|1
typedef long long LL;
typedef pair<double, double> PII;
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 buf[]) {
        int len = strlen(buf);
        int now = root;
        for(int i = 0; i < len; i++) {
            if(next[now][buf[i] - ‘a‘] == -1)
                next[now][buf[i] - ‘a‘] = newnode();
            now = next[now][buf[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 buf[]) {
        int len = strlen(buf);
        int now = root;
        int res = 0;
        for(int i = 0; i < len; i++) {
            now = next[now][buf[i] - ‘a‘];
            int temp = now;
            while( temp != root ) {
                res += end[temp];
                end[temp] = 0;
                temp = fail[temp];
            }
        }
        return res;
    }
    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");
        }
    }
};
Trie AC;
char s[1000005];
int main() {
    //FIN
    int T;
    scanf("%d", &T);
    while(T--) {
        AC.init();
        int n;
        scanf("%d", &n);
        for(int i = 1; i <= n; i++) {
            scanf("%s", s);
            AC.insert(s);
        }
        AC.build();
        scanf("%s", s);
        printf("%d\n", AC.query(s));
    }
    return 0;
}
HDU 2222 Keywords Search AC自动机
原文:http://www.cnblogs.com/Hyouka/p/7450827.html