211_Add_and_search_word

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

class WordDictionary {

    /** Initialize your data structure here. */
    private class TrieNode {
        Map<Character,TrieNode> children;
        boolean endOfWord;
        TrieNode() {
            children = new HashMap<Character,TrieNode>();
            endOfWord = false;
        }
    }
    private final TrieNode root;
    public WordDictionary() {
        root = new TrieNode();
    }
    
    /** Adds a word into the data structure. */
    public void addWord(String word) {
        TrieNode current = root;
        for(int i=0;i<word.length();i++) {
            char ch = word.charAt(i);
            TrieNode node = current.children.get(ch);
            if(node == null) {
                node = new TrieNode();
                current.children.put(ch,node);
            }
            current = node;
        }
        current.endOfWord = true;
    }
    
    /** Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter. */
    public boolean search(String word) {
        // TrieNode current = root;
        // for(int i=0;i<word.length();i++) {
        //     char ch = word.charAt(i);
        //     if(ch == '.')
        //         TrieNode node = chooseLetter(current, i, word);
        //     else
        //         TrieNode node = current.children.get(ch);
        //     if(node == null)
        //         return false;
        //     current = node;
        // }
        // return current.endOfWord;
        return search(word, 0 ,root);
    }
    public boolean search(String word, int idx, TrieNode node) {
       if(idx == word.length())
           return node.endOfWord;
        if(word.charAt(idx)=='.') {
            for(char c:node.children.keySet()) {
                if(search(word,idx+1,node.children.get(c)))
                    return true;
            }
        }
        else {
            if(node.children.get(word.charAt(idx))!=null) {
                return search(word,idx+1,node.children.get(word.charAt(idx)));
            }
        }
        return false;
    }
}

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