211. 添加与搜索单词 - 数据结构设计

https://leetcode.cn/problems/design-add-and-search-words-data-structure/description/?envType=study-plan-v2&envId=top-interview-150

思路：就是然我们设计一个字典树，和上一题基本一样，之前使用的是树的方式来构建字典树。

class Main{class WordDictionary {private WordDictionary[] children;private boolean isEnd;public WordDictionary() {this.children = new WordDictionary[26];this.isEnd = false;}public void addWord(String word) {WordDictionary node = this;for (int i = 0; i < word.length(); i++) {char ch = word.charAt(i);int index = ch - 'a';if (node.children[index] == null) {node.children[index] = new WordDictionary();}node = node.children[index];}node.isEnd = true;}public boolean search(String word) {WordDictionary node = this;return search2(node, word, 0);}public boolean search2(WordDictionary node, String word, int index) {if(index == word.length()) {return node.isEnd;}//遇到'.' 的逻辑：遍历该层的所有非空节点只要所有情况中存在匹配情况就返回true(意思就是只有true才是终点)char ch = word.charAt(index);if(ch == '.') {for(WordDictionary child : node.children) {if( child != null) {if(search2(child, word, index + 1)) {return true;}}}} else {if(node.children[ch - 'a'] != null && search2(node.children[ch - 'a'], word, index + 1)) {return true;}}return false;}}public static void main(String[] args) {Main main = new Main();WordDictionary wordDictionary = main.new WordDictionary();wordDictionary.addWord("bad");wordDictionary.addWord("dad");wordDictionary.addWord("mad");System.out.println(wordDictionary.search("pad")); // return falseSystem.out.println(wordDictionary.search("bad")); // return trueSystem.out.println(wordDictionary.search(".ad")); // return trueSystem.out.println(wordDictionary.search("b..")); // return true}}