HDU 2222 Keywords Search AC自动机

  1 // File Name: temp.cpp
  2 // Author: darkdream
  3 // Created Time: 2014年09月11日 星期四 15时18分26秒
  4 
  5 #include<vector>
  6 #include<list>
  7 #include<map>
  8 #include<set>
  9 #include<deque>
 10 #include<stack>
 11 #include<bitset>
 12 #include<algorithm>
 13 #include<functional>
 14 #include<numeric>
 15 #include<utility>
 16 #include<sstream>
 17 #include<iostream>
 18 #include<iomanip>
 19 #include<cstdio>
 20 #include<cmath>
 21 #include<cstdlib>
 22 #include<cstring>
 23 #include<ctime>
 24 #include<queue>
 25 #define LL long long
 26 #define maxn 500010
 27 using namespace std;
 28 struct Trie
 29 {
 30    int next[maxn][26],fail[maxn],end[maxn];
 31    int root, L;
 32    int newnode()
 33    {
 34        for(int i = 0 ;i < 26;i ++)
 35           next[L][i] = -1;
 36        end[L++] = 0 ;
 37        return L-1;
 38    }
 39    int init()
 40    {
 41       int L = 0 ; 
 42       root = newnode();
 43    }
 44    int insert(char buf[])
 45    {
 46       int len = strlen(buf);
 47       int now = root;
 48       for(int i = 0 ;i < len ;i ++)
 49       {
 50          if(next[now][buf[i] - ‘a‘] ==  -1)
 51          {
 52              next[now][buf[i] - ‘a‘] = newnode();
 53          }
 54          now = next[now][buf[i]-‘a‘];
 55       }
 56       end[now]++;
 57    }
 58    void build()
 59    {
 60        queue<int> Q; 
 61        //这里为何要用优先队列来解决这个问题，主要原因是fail指针是按层数来的。
 62        fail[root] = root; 
 63        for(int i = 0;i < 26;i ++)
 64        {
 65             if(next[root][i] == -1)
 66             {
 67                next[root][i] = root;  //指向root 是没有问题的，我们主要是通过end 数组对个数进行计数的。    
 68             }else{
 69                fail[next[root][i]] = root;
 70                Q.push(next[root][i]);
 71             }
 72        }
 73        while(!Q.empty())
 74        {
 75           int now = Q.front();
 76           Q.pop();
 77           for(int i = 0 ;i < 26;i ++)
 78           {
 79              if(next[now][i] == -1)
 80                  next[now][i] =  next[fail[now]][i]; 
 81              else{
 82                 fail[next[now][i]] = next[fail[now]][i];
 83                 Q.push(next[now][i]);
 84              }
 85           }
 86        }
 87    }
 88    int query(char buf[])
 89    {
 90       int len = strlen(buf);
 91       int now = root ; 
 92       int res = 0 ; 
 93       for(int i = 0 ;i < len;i ++)
 94       {
 95         now = next[now][buf[i] -‘a‘];
 96         int temp = now ; 
 97         while(temp != root)
 98         {
 99            res += end[temp];
100            end[temp] = 0 ; 
101            temp = fail[temp];//  不断的寻找 fail 指针 因为会出线这样的字符串  abcd bcd cd
102         }
103       }
104       return res;
105    }
106 };
107 char buf[1000010];
108 Trie ac;
109 int main(){
110     int T;
111     int n;
112     scanf("%d",&T);
113     {
114       while(T--)
115       {
116          scanf("%d",&n);
117          ac.init();
118          for(int i = 0 ;i < n;i ++)
119          {
120             scanf("%s",buf);
121             ac.insert(buf);
122          }
123          ac.build();
124          scanf("%s",buf);
125          printf("%d\n",ac.query(buf));
126       }
127     }
128 return 0;
129 }