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 }