hdu 2222 Keywords Search (AC自动机-初步-很理解！)

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <string>
#include <queue>
#include <algorithm>
#define BUG cout << "here\n";
using namespace std;
#define kind 26
#define M 1000010

struct node {
node* fail;
node* next[kind];
int tail;
node() {
fail = NULL;
tail = 0;
memset(next, 0, sizeof(next));
}
};
char ch[M];
char word[M];
queue<node*> Q;
int n, m;
void Insert(node* root, char *str) {
node* p = root;
int i = 0, index;
int len = strlen(str);
for(i = 0; i < len; i++) {
index = str[i] - 'a';
if(p->next[index] == NULL) {
p->next[index] = new node();
}
p = p->next[index];
}
p->tail++;
}
void BFS_AC(node*& root) { // 指针引用, 就是广搜模式建立失败指针， 核心 ： 当前节点父节点失败指针的儿子
Q.push(root);
while(!Q.empty()) {
node* p = NULL;
node* t = Q.front();
Q.pop();
for(int i = 0; i < kind; i++) {
if(t->next[i]) {
p = t->fail;
while(p) {
if(p->next[i]) {
t->next[i]->fail = p->next[i];
break;
}
p = p->fail;
}
if(!p) {
t->next[i]->fail = root;
}
Q.push(t->next[i]);
}
}
}
}
void Query(node* root, char *str) {
int i = 0, index, cnt = 0;
node *p = root, *tmp;
int len = strlen(str);

for(i = 0; i < len; i++) {
index = str[i] - 'a';
while(!p->next[index] && p != root) {
p = p->fail;
}
p = p->next[index];
if(!p) p = root; // 标志了！
tmp = p;
while(tmp != root && tmp->tail != -1) {
cnt += tmp->tail;
tmp->tail = -1;
tmp = tmp->fail;
}
}
cout << cnt << endl;
}
int main() {
int T;
cin >> T;
while(T--) {
scanf("%d", &n);
node* root = new node();
for(int i = 0; i < n; i++) {
scanf("%s", ch);
Insert(root, ch);
}
BFS_AC(root);
scanf("%s", word);
Query(root, word);
}
return 0;
}