HDU - 2222 Keywords Search （AC自动机）

 3 
题意：求单词出现的次数
思路：第一题AC自动机，套了模板
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int kind = 26;

struct Node {
	Node *fail;
	Node *next[kind];
	int count;
	Node() {
		fail = NULL;
		count = 0;
		for (int i = 0; i < kind; i++)
			next[i] = NULL;
	}
} *q[500001];
char keyword[51];
char str[1000001];
int head, tail;

void insert(char *str, Node *root) {
	Node *p = root;
	int i = 0, index;
	while (str[i]) {
		index = str[i] - 'a';
		if (p->next[index] == NULL)
			p->next[index] = new Node();
		p = p->next[index];
		i++;
	}
	p->count++;
}

void buildAcAutomation(Node *root) {
	int i;
	root->fail = NULL;
	q[head++] = root;
	while (head != tail) {
		Node *temp = q[tail++];
		Node *p = NULL;
		for (int i = 0; i < 26; i++) {
			if (temp->next[i] != NULL) {
				if (temp == root) temp->next[i]->fail = root;
				else {
					p = temp->fail;
					while (p != NULL) {
						if (p->next[i] != NULL) {
							temp->next[i]->fail = p->next[i];
							break;
						}
						p = p->fail;
					}
					if (p == NULL)
						temp->next[i]->fail = root;
				}
				q[head++] = temp->next[i];
			}
		}
	}
}

int query(Node *root) {
	int i = 0, cnt = 0, index, len = strlen(str);
	Node *p = root;
	while (str[i]) {
		index = str[i] - 'a';
		while (p->next[index] == NULL && p != root) p = p->fail;
		p = p->next[index];
		p = (p == NULL) ? root : p;
		Node *temp = p;
		while (temp != root && temp->count != -1) {
				cnt += temp->count;
				 temp->count = -1;
				 temp = temp->fail;
			}
			i++;
	}
	return cnt;	
}

void del(Node *root) {
	for (int i = 0; i < kind; i++)
		if (root->next[i] != NULL)
			del(root->next[i]);
	free(root);
}

int main() {
	int n, t;
	scanf("%d", &t);
	while (t--) {
		head = tail = 0;
		Node *root = new Node();
		scanf("%d", &n);
		getchar();
		while (n--) {
			gets(keyword);
			insert(keyword, root);
		}
		buildAcAutomation(root);
		scanf("%s", str);
		printf("%d\n", query(root));
		del(root);
	}
	return 0;
}