HDU 2222 AC自动机模板题

题目： http://acm.hdu.edu.cn/showproblem.php?pid=2222

AC自动机模板题

我现在对AC自动机的理解还一般，就贴一下我参考学习的两篇博客的链接：

http://blog.csdn.net/niushuai666/article/details/7002823

http://www.cppblog.com/menjitianya/archive/2014/07/10/207604.html

 1 #include<stdio.h>
 2 #include<string.h>
 3 #include<queue>
 4 using namespace std;
 5 char key[55];
 6 char des[1111111];
 7 struct node{
 8     node *fail;
 9     node *next[26];
10     int cnt;
11     node(){
12         fail = NULL;
13         cnt = 0;
14         for(int i = 0;i<26;i++)
15             next[i] = NULL;
16     }
17 };
18 node *root;
19 void insert(char *str){
20     node *head = root;
21     int len = strlen(str);
22     for(int i = 0;i<len;i++){
23         int temp = str[i]-'a';
24         if(head->next[temp] == NULL)
25             head->next[temp] = new node();
26         head = head->next[temp];
27     }
28     head->cnt++;
29 } 
30 void build(){
31     queue<node *>q;
32     q.push(root);
33     while(!q.empty()){
34         node *head = q.front();
35         q.pop();
36         for(int i = 0;i<26;i++){
37             if(head->next[i] != NULL){
38                 if(head == root){
39                     head->next[i]->fail = root;
40                 }else{
41                     node *temp = head->fail;
42                     while(temp != NULL){
43                         if(temp->next[i] != NULL){
44                             head->next[i]->fail = temp->next[i];
45                             break;
46                         }
47                         temp = temp->fail;
48                     }
49                     if(temp == NULL)
50                         head->next[i]->fail = root;
51                 }
52                 q.push(head->next[i]);
53             }
54         }
55     }
56 }
57 int query(){
58     int len = strlen(des),ans = 0;;
59     node *head = root;
60     for(int i = 0;i<len;i++){
61         int index = des[i]-'a';
62         while(head->next[index] == NULL && head != root)
63             head = head->fail;
64         head = head->next[index];
65         if(head == NULL)
66             head = root;
67         node *temp = head;
68         while(temp!=root && temp->cnt!=-1){
69             ans += temp->cnt;
70             temp->cnt = -1;
71             temp = temp->fail;
72         }
73     }
74     return ans;
75 }
76 int main(){
77     int t;
78     scanf("%d",&t);
79     while(t--){
80         root = new node();
81         int n;
82         scanf("%d",&n);
83         for(int i = 0;i<n;i++){
84             scanf(" %s",key);
85             insert(key);
86         }
87         build();
88         scanf(" %s",des);
89         printf("%d
",query());
90     }    
91     return 0;
92 }