leetcode208

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 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：

 1 class TrieNode:
 2     def __init__(self):
 3         self.words = 0
 4         self.prefixs = 0
 5         self.edges = [None] * 26
 6 
 7 class Trie:
 8     def __init__(self):
 9         self.root = TrieNode()
10 
11     def insert(self,word):
12         self.insertHelper(self.root,word,0)
13 
14     def search(self,word):
15         return self.searchHelper(self.root,word,0) != 0
16 
17     def startsWith(self,prefix):
18         return self.startsWithHelper(self.root,prefix,0) != 0
19 
20     def insertHelper(self,node,word,pos):
21         if pos == len(word):
22             node.words += 1
23             node.prefixs += 1
24         else:
25             node.prefixs += 1
26             char_code = ord(word[pos]) - 97
27             if node.edges[char_code] == None:
28                 node.edges[char_code] = TrieNode()
29             self.insertHelper(node.edges[char_code],word,pos+1)
30 
31     def searchHelper(self,node,word,pos):
32         if pos == len(word):
33             return node.words
34         else:
35             char_code = ord(word[pos]) - 97
36             if node.edges[char_code] == None:
37                 return 0
38             else:
39                 return self.searchHelper(node.edges[char_code],word,pos+1)
40 
41     def startsWithHelper(self,node,word,pos):
42         if pos == len(word):
43             return node.prefixs
44         else:
45             char_code = ord(word[pos]) - 97
46             if node.edges[char_code] ==  None:
47                 return 0
48             else:
49                 return self.startsWithHelper(node.edges[char_code],word,pos+1)

posted on 2018-10-06 09:49 Sempron2800+ 阅读(336) 评论(0) 编辑收藏举报