hdu 1277 全文检索

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思路：AC自动机模板题
分析：
1 只要把输入处理成一个字符串，然后对关键字建立trie树和求next
2 注意题目是说按照匹配到的顺序输出，所以这个地方注意一下。

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
using namespace std;

#define MAXN 600010
#define MAX 10010
#define N 15

int n , m , cnt;
char text[MAXN];
struct Node{
   Node *next;
   Node *child[N];
   int number;
};
Node node[MAXN];
Node *root;
queue<Node*>q;

Node* newNode(){
   node[cnt].next = NULL;
   node[cnt].number = 0;
   for(int i = 0 ; i < N ; i++)
      node[cnt].child[i] = NULL;
   return &node[cnt++];
}

void insert(char *str , int x){
  int len = strlen(str);
  Node *p = root;

  for(int i = 0 ; i < len ; i++){
     int num = str[i]-'0';
     if(p->child[num] == NULL)
       p->child[num] = newNode();
     p = p->child[num];
  }
  p->number = x;
}

void getNext(){
   while(!q.empty())
       q.pop();

   q.push(root);
   root->next = NULL;

   while(!q.empty()){
      Node *p = q.front();
      q.pop();
      for(int i = 0 ; i < N ; i++){
         if(p->child[i]){
           q.push(p->child[i]);
           Node *tmp = p->next;

           while(tmp){
              if(tmp->child[i]){
                p->child[i]->next = tmp->child[i];
                break;
              }
              tmp = tmp->next;
           }
           if(tmp == NULL)
             p->child[i]->next = root;
         }
      }
   }
}

bool find(){
    int len = strlen(text);
    bool mark = false;
    Node *p = root;

    for(int i = 0 ; i < len ; i++){
       int num = text[i]-'0';
       while(p->child[num] == NULL && p != root)
           p = p->next;
       if(p->child[num]){
         p = p->child[num];
         Node *tmp = p;
         while(tmp){
            if(tmp->number){
              if(!mark){
                printf("Found key:");
                mark = true;
              }
              printf(" [Key No. %d]" , tmp->number);
            }
            tmp = tmp->next;
         }
       }
    }
    return mark;
}

int main(){
   char str[MAXN];
   while(scanf("%d%d%*c" , &n , &m) != EOF){
      cnt = 0;
      root = newNode();
      
      for(int i = 0 ; i < n ; i++){
         gets(str);
         strcat(text , str);
      }

      int len = strlen(text);
      text[len] = '\0';
      gets(str);/*读掉空行*/

      for(int i = 0 ; i < m ; i++){
         gets(str);
         for(int j = 1 ; j < n ; j++){
            if(str[j] == ' ' && str[j-1] == ']'){
              insert(str+j+1 , i+1);
              break;
            }
         }
      }
      getNext();
      if(!find())
        printf("No key can be found !");
      printf("\n");
   }
   return 0;
}