添加与搜索单词 - 数据结构设计

/*
 * 题目思路：
 * 1. 使用 Trie 树存储添加的单词，每个节点代表一个字母。
 * 2. 利用 Java Stream 流式操作优化搜索通配符 '.' 的逻辑。
 */
import java.util.*;
import java.util.stream.*;
 
public class WordDictionary {
    private TrieNode root;
 
    public WordDictionary() {
        root = new TrieNode();
    }
 
    // Trie 树节点类
    private class TrieNode {
        private TrieNode[] children;
        private boolean isEnd;
 
        public TrieNode() {
            children = new TrieNode[26];
            isEnd = false;
        }
    }
 
    // 添加单词到 Trie 树
    public void addWord(String word) {
        TrieNode node = root;
        for (char c : word.toCharArray()) {
            if (node.children[c - 'a'] == null) {
                node.children[c - 'a'] = new TrieNode();
            }
            node = node.children[c - 'a'];
        }
        node.isEnd = true;
    }
 
    // 查找单词或通配符组合
    public boolean search(String word) {
        return search(word, root);
    }
 
    private boolean search(String word, TrieNode node) {
        for (int i = 0; i < word.length(); i++) {
            char c = word.charAt(i);
            if (c == '.') {
                return Arrays.stream(node.children)
                        .filter(Objects::nonNull)
                        .anyMatch(child -> search(word.substring(i + 1), child));
            } else {
                if (node.children[c - 'a'] == null) {
                    return false;
                }
                node = node.children[c - 'a'];
            }
        }
        return node.isEnd;
    }
}