Leetcode 211. Design Add and Search Words Data Structure

方法1: 和208题一样，都是trie数据结构。不是很难，直接上代码。

class TrieNode {
    public char val;
    public boolean isEnd;
    public TrieNode[] children = new TrieNode[26];
    public TrieNode(){}
    TrieNode(char c){
        this.val = c;
        TrieNode node = new TrieNode();
    }
}

class WordDictionary {
    TrieNode root;
    /** Initialize your data structure here. */
    public WordDictionary() {
        this.root = new TrieNode(' ');
    }
    
    public void addWord(String word) {
        TrieNode node = root;
        for(int i = 0; i < word.length(); i++){
            char c = word.charAt(i);
            if(node.children[c - 'a'] == null){
                node.children[c - 'a'] = new TrieNode(c);
            }
            node = node.children[c - 'a'];
        }
        node.isEnd = true;
    }
    
    public boolean search(String word) {
        TrieNode node = root;
        return helper(0, node, word);
    }
    
    public boolean helper(int start, TrieNode node, String word){
        if(start == word.length()) return node.isEnd;
        char c = word.charAt(start);
        if(c == '.'){
            boolean flag = true;
            for(int j = 0; j < 26; j++){
                if(node.children[j] != null){
                    flag = false;
                    if(helper(start + 1, node.children[j], word)) return true;
                }
            }
            if(flag) return false;
        }else{
            if(node.children[c - 'a'] == null){
                return false;
            }else{
                return helper(start + 1, node.children[c - 'a'], word);
            }
        }
        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);
 */

总结：

• 无