学习链接:
http://www.cppblog.com/mythit/archive/2009/04/21/80633.html
http://blog.csdn.net/niushuai666/article/details/7002736
http://www.cnblogs.com/kuangbin/category/402395.html
hdu 2222 代码:
1 #include <vector> 2 #include <map> 3 #include <set> 4 #include <algorithm> 5 #include <iostream> 6 #include <cstdio> 7 #include <cmath> 8 #include <cstdlib> 9 #include <string> 10 #include <cstring> 11 #include <queue> 12 #include <stack> 13 using namespace std; 14 15 #define N 1000010 16 17 char str[N],key[111]; 18 int head,tail; 19 20 struct node 21 { 22 node *fail; 23 node *next[26]; 24 int count; 25 node(){ 26 fail=NULL; 27 count=0; 28 for(int i=0; i<26; i++) 29 next[i]=NULL; 30 } 31 }*q[N]; 32 33 node *root; 34 35 void insert(char *str) //建立Trie 36 { 37 int temp,len; 38 node *p=root; 39 len=strlen(str); 40 for(int i=0; i<len; i++){ 41 temp=str[i]-'a'; 42 if(p->next[temp] == NULL) 43 p->next[temp]=new node(); 44 p=p->next[temp]; 45 } 46 p->count++; 47 } 48 49 void build_ac() //初始化fail指针，BFS 50 { 51 q[tail++]=root; 52 while(head != tail){ 53 node *p=q[head++]; //弹出队头 54 node *temp=NULL; 55 for(int i=0; i<26; i++){ 56 if(p->next[i] != NULL){ 57 if(p==root) //第一个元素fail必指向根 58 p->next[i]->fail=root; 59 else{ 60 temp=p->fail; //失败指针 61 while(temp!=NULL){ //2种情况结束：匹配为空or找到匹配 62 if(temp->next[i]!=NULL){ //找到匹配 63 p->next[i]->fail=temp->next[i]; 64 break; 65 } 66 temp=temp->fail; 67 } 68 if(temp==NULL) //为空则从头匹配 69 p->next[i]->fail=root; 70 } 71 q[tail++]=p->next[i]; //入队 72 } 73 } 74 } 75 } 76 77 int query() //扫描 78 { 79 int index,len,ans=0; 80 node *p=root; //Tire入口 81 len=strlen(str); 82 for(int i=0; i<len; i++){ 83 index=str[i]-'a'; 84 while(p->next[index]==NULL && p!=root) //跳转失败指针 85 p=p->fail; 86 p=p->next[index]; 87 if(p==NULL) 88 p=root; 89 node *temp=p; //p不动，temp计算后缀串 90 while(temp!=root && temp->count!=-1){ 91 ans+=temp->count; 92 temp->count=-1; 93 temp=temp->fail; 94 } 95 } 96 return ans; 97 } 98 99 int main() 100 { 101 int t,num; 102 scanf("%d",&t); 103 while(t--){ 104 head=tail=0; 105 root=new node(); 106 scanf("%d",&num); 107 //getchar(); 108 for(int i=0; i<num; i++){ 109 scanf("%s",key); 110 insert(key); 111 } 112 build_ac(); 113 scanf("%s",str); 114 printf("%d ",query()); 115 } 116 }