leetcode208

class TrieNode {
public:
    // Initialize your data structure here.
    TrieNode() {
            words=;
            prefixs=;
            for(int i=;i<;i++)
               edges[i]=NULL;
        }
        int words;
        int prefixs;
        TrieNode* edges[];
};

class Trie {
public:
    Trie() {
        root = new TrieNode();
    }

    // Inserts a word into the trie.
    void insert(string word) {
            insertHelper(root,word,);
    }

    // Returns if the word is in the trie.
    bool search(string word) {
            return searchHelper(root,word,)!=;
    }

    // Returns if there is any word in the trie
    // that starts with the given prefix.
    bool startsWith(string prefix) {
            return startsWithHelper(root,prefix,)!=;
    }

    void insertHelper(TrieNode * node,string &word,int pos) {
        if(pos==word.size())
        {
            node->words++;
            node->prefixs++;
        }
        else
        {
            node->prefixs++;
            int char_code=word[pos]-'a';
            if(node->edges[char_code]==NULL)
                node->edges[char_code]=new TrieNode();
            insertHelper(node->edges[char_code],word,pos+);
        }
    }

    int searchHelper(TrieNode * node,string &word,int pos)
    {
        int char_code=word[pos]-'a';
        if(pos==word.size())
            return node->words;
        else if(node->edges[char_code]==NULL)
            return ;
        else
            return searchHelper(node->edges[char_code],word,pos+);
    }

    int startsWithHelper(TrieNode * node,string &word,int pos)
    {
        int char_code=word[pos]-'a';
        if(pos==word.size())
            return node->prefixs;
        else if(node->edges[char_code]==NULL)
            return ;
        else
            return startsWithHelper(node->edges[char_code],word,pos+);
    }

private:
    TrieNode* root;
};

/**
 * Your Trie object will be instantiated and called as such:
 * Trie obj = new Trie();
 * obj.insert(word);
 * bool param_2 = obj.search(word);
 * bool param_3 = obj.startsWith(prefix);
 */

补充一个python的实现：

 class TrieNode:
     def __init__(self):
         self.words = 0
         self.prefixs = 0
         self.edges = [None] * 26

 class Trie:
     def __init__(self):
         self.root = TrieNode()

     def insert(self,word):
         self.insertHelper(self.root,word,0)

     def search(self,word):
         return self.searchHelper(self.root,word,0) != 0

     def startsWith(self,prefix):
         return self.startsWithHelper(self.root,prefix,0) != 0

     def insertHelper(self,node,word,pos):
         if pos == len(word):
             node.words += 1
             node.prefixs += 1
         else:
             node.prefixs += 1
             char_code = ord(word[pos]) - 97
             if node.edges[char_code] == None:
                 node.edges[char_code] = TrieNode()
             self.insertHelper(node.edges[char_code],word,pos+1)

     def searchHelper(self,node,word,pos):
         if pos == len(word):
             return node.words
         else:
             char_code = ord(word[pos]) - 97
             if node.edges[char_code] == None:
                 return 0
             else:
                 return self.searchHelper(node.edges[char_code],word,pos+1)

     def startsWithHelper(self,node,word,pos):
         if pos == len(word):
             return node.prefixs
         else:
             char_code = ord(word[pos]) - 97
             if node.edges[char_code] ==  None:
                 return 0
             else:
                 return self.startsWithHelper(node.edges[char_code],word,pos+1)