AC automation 模板

  1 /*
  2 1.对n个字符串构造tire树                        insertWord(node *root, char *word);
  3 2.bfs构造fail指针                    makeFail(node *root);
  4 3.基于以上两点的查询                query(node *root, char *str);
  5 */
  6 #include <stdio.h>
  7 #include <string.h>
  8 #include <queue>
  9 using namespace std;
 10 const int N1 = 50 + 10;
 11 const int N2 = 1000000 + 10;
 12 char key[N1];
 13 char desc[N2];
 14 struct node
 15 {
 16     node *next[26];
 17     int cnt;
 18     node *fail;
 19     node(){for(int i=0; i<26; ++i) next[i] = NULL; fail = NULL; cnt = 0;}
 20 };
 21 void insertWord(node *root)//构造trie树
 22 {
 23     node *cur = root;
 24     int n = strlen(key);
 25     for(int i=0; i<n; ++i)
 26     {
 27         int index = key[i] - ‘a‘;
 28         if(cur->next[index] != NULL)
 29             cur = cur->next[index];
 30         else
 31         {
 32             cur->next[index] = new node();
 33             cur = cur->next[index];
 34         }
 35     }
 36     cur->cnt++;
 37 }
 38 void makeFail(node *root)//构造fail指针
 39 {
 40     queue<node*> q;
 41     q.push(root);
 42     node *cur;
 43     while(!q.empty())
 44     {    
 45         cur = q.front();
 46         q.pop();
 47         for(int i=0; i<26; ++i)
 48         {
 49             if(cur->next[i] != NULL)
 50             {
 51                 if(cur == root)//与root相连的结点，即第二层的结点的fail指针都是root
 52                     cur->next[i]->fail = root;
 53                 else
 54                 {
 55                     node *tmp = cur;
 56                     while(tmp->fail != NULL)// why while?
 57                     {
 58                         if(tmp->fail->next[i] != NULL)
 59                         {
 60                             cur->next[i]->fail = tmp->fail->next[i];
 61                             break;
 62                         }                            
 63                         tmp = tmp->fail;
 64                     }
 65                     if(tmp->fail == NULL)
 66                         cur->next[i]->fail = root;
 67                 }
 68                 q.push(cur->next[i]);
 69             }
 70         }
 71     }
 72 }
 73 int query(node *root)//查询
 74 {
 75     node *cur = root;
 76     node *tmp = NULL;
 77     int i=0,cnt=0;
 78     while(desc[i])
 79     {
 80         int index = desc[i] - ‘a‘;
 81         while(cur!=root && cur->next[index] == NULL)
 82             cur = cur->fail;
 83         if(cur->next[index] != NULL)
 84         {
 85             cur = cur->next[index];
 86             tmp = cur;
 87             while(tmp != root && tmp->cnt!=0)
 88             {
 89                 cnt += tmp->cnt;
 90                 tmp->cnt = 0;
 91                 tmp = tmp->fail;
 92             }
 93         }
 94         i++;
 95     }
 96     return cnt;
 97 }
 98 int main()
 99 {
100     int t,n;
101     scanf("%d",&t);
102     while(t--)
103     {
104         node *root = new node();
105         scanf("%d",&n);
106         for(int i=0; i<n; ++i)
107         {
108             scanf("%s",key);
109             insertWord(root);
110         }
111         makeFail(root);
112         scanf("%s",desc);
113         int ans = query(root);
114         printf("%d\n",ans);
115     }
116     return 0;
117 }