leetcode-211 Add and Search Word - Data structure design

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Design a data structure that supports the following two operations:

  • void addWord(word)
  • bool search(word)

search(word) can search a literal word or a regular expression string containing only letters a-z or .. A . means it can represent any one letter.

Example:

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addWord("bad")
addWord("dad")
addWord("mad")
search("pad") -> false
search("bad") -> true
search(".ad") -> true
search("b..") -> true

Note:

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

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class TrieNode{
public:
    bool word;
    TrieNode* children[26];
    TrieNode(){
        word = false;
        memset(children, NULL, sizeof(children));
    }
};



class WordDictionary {
public:
    /** Initialize your data structure here. */
    WordDictionary() {
        
    }
    
    /** Adds a word into the data structure. */
    void addWord(string word) {
        TrieNode* node = root;
        for(char c: word)
        {
            if(!node->children[c-'a']){
                node->children[c-'a'] = new TrieNode();
            }
            node = node->children[c-'a'];
        }
        node->word = 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) {
        return search(word.c_str(), root);
    }

private:
    TrieNode* root = new TrieNode();
    
    bool search(const char* word, TrieNode* node){
        for(int i=0; word[i] && node; i++){
            if(word[i] != '.'){
                node = node->children[word[i]-'a'];
            }
            else{
                TrieNode* tmp = node;
                for(int j=0; j<26; j++){
                    node = tmp->children[j];
                    if(search(word+i+1, node)){
                        return true;
                    }
                }
            }
        }
        return node && node->word;
    }
};

/**
 * Your WordDictionary object will be instantiated and called as such:
 * WordDictionary* obj = new WordDictionary();
 * obj->addWord(word);
 * bool param_2 = obj->search(word);
 */
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