leetcode:Trie:Add and Search Word - Data structure design(211)

https://leetcode.com/problems/add-and-search-word-data-structure-design/

---

class TrieNode  
{  
public:  
    bool isEnd;  
    TrieNode *children[26];  
    TrieNode() : isEnd(false)  
    {  
        for (int i = 0; i < 26; i++)  
        {  
            children[i] = NULL;  
        }  
    }  
};  

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

    // Adds a word into the data structure.  
    void addWord(string word) {  
        TrieNode *cur = root;  
        for (int i = 0; i < word.length(); i++)  
        {  
            int index = word[i] - 'a';  
            if (cur->children[index] == NULL)  
            {  
                cur->children[index] = new TrieNode();  
            }  

            cur = cur->children[index];  
        }  

        cur->isEnd = true;   
    }  

    // Returns if the word is in the data structure. A word could  
    // contain the dot character '.' to represent any one letter.  
    bool search(string word) {  
        int n = word.length();  
        return search(word, n, 0, root);  
    }  

    bool search(string &word, int n, int pos, TrieNode *cur)  
    {  
        if (cur == NULL)  
        {  
            return false;  
        }  
        if (pos == n)  
        {  
            return cur->isEnd;  
        }  

        if (word[pos] == '.')  
        {  
            for (int i = 0; i < 26; i++)  
            {  
                if (cur->children[i])  
                {  
                    if (search(word, n, pos+1, cur->children[i]))  
                    {  
                        return true;  
                    }  
                }  
            }  
        }  
        else  
        {  
            int index = word[pos] - 'a';  
            if (cur->children[index])  
            {  
                return search(word, n, pos+1, cur->children[index]);  
            }  
        }  

        return false;  
    }  
private:  
    TrieNode *root;  
};