字典树模板

第一次接触字典树的实现，先看到了一个指针实现的模板，觉得很好理解，用着也方便，先收集过来 :)

//字典树用来查询有公共前缀的单词有多少个，插入和查询的时间复杂度均为O（n)

#include < iostream >
#include < cstring >
#define  N 300  // 有N个单词
#define  M 1000000 // 有M次查询
#define  kind 26 // 26个英文字母
using   namespace  std;
struct  Treenode
{
     int  count;
    Treenode  * next[kind];
    Treenode(){
         for ( int  i = 0 ; i < kind; i ++ )
            next[i] = NULL;
        count = 1 ;
    }
};
void  insert(Treenode  *& root,  char   * word)
{
     int  i = 0 ,j,l = strlen(word),branch;
    Treenode  * location = root;
     if (location == NULL){
        location = new  Treenode();
        root = location;
    }

     for (i = 0 ; i < l; i ++ ){
        branch = word[i] - ' a ' ;
         if (location -> next[branch])
            location -> next[branch] -> count ++ ;
         else
            location -> next[branch] = new  Treenode();
        location = location -> next[branch];
    }
}
int  search(Treenode  *& root,  char   * word)
{
     int  i, ans = 0 , l = strlen(word),branch;
    Treenode  * location = root;
     if (location == NULL)  return   0 ;
     for (i = 0 ; i < l; i ++ ){
        branch = word[i] - ' a ' ;
         if ( ! location -> next[branch])
             return   0 ;

        location = location -> next[branch];
        ans = location -> count;
    }
     return  ans;
}

int  main()
{
     int  i,j,n,m;
     char  word[ 50 ];
    Treenode  * root = NULL;
    scanf( " %d " ,  & n);
     for (i = 0 ; i < n; i ++ ){
        scanf( " %s " ,word);
        insert(root, word);
    }
    scanf( " %d " , & m);
     for (i = 0 ; i < m; i ++ ){
        scanf( " %s " ,word);
        printf( " %d\n " ,search(root, word));
    }

     return   0 ;
}