Implement a trie with insert, search, and startsWith methods.

Note:

You may assume that all inputs are consist of lowercase letters a-z.

Hide Tags Data Structure Trie

实现一棵Trie树以及实现查询的功能，依据中的分析和伪代码能够非常迅速地实现：

runtime:68ms

class TrieNode {public:    // Initialize your data structure here.    TrieNode() {            words=0;            prefixs=0;            for(int i=0;i<26;i++)               edges[i]=NULL;         }        int words;        int prefixs;        TrieNode* edges[26];};class Trie {public:    Trie() {        root = new TrieNode();    }    // Inserts a word into the trie.    void insert(string word) {            insertHelper(root,word,0);    }    // Returns if the word is in the trie.    bool search(string word) {            return searchHelper(root,word,0)!=0;    }    // Returns if there is any word in the trie    // that starts with the given prefix.    bool startsWith(string prefix) {            return startsWithHelper(root,prefix,0)!=0;    }    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+1);        }    }    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 0;        else             return searchHelper(node->edges[char_code],word,pos+1);    }    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 0;        else            return startsWithHelper(node->edges[char_code],word,pos+1);    }private:    TrieNode* root;};// Your Trie object will be instantiated and called as such:// Trie trie;// trie.insert("somestring");// trie.search("key");