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.
For example:
addWord("bad")
addWord("dad")
addWord("mad")
search("pad") -> false
search("bad") -> true
search(".ad") -> true
search("b..") -> true
设计一个字典树的数据结构,实现add和search功能,对于search功能,加了一个模糊匹配搜索,字符' . '可以代表任意一个字符,因此当我们匹配到' . '字符时,我们可以用回溯法从当前字符往下找,如果可以找到就返回true,如果不能找到就回溯从其他点开始。代码如下:
class TrieNode { TrieNode[] trieNode; boolean isLast; public TrieNode() { trieNode = new TrieNode[26]; isLast = false; } } public class WordDictionary { private TrieNode root; public WordDictionary() { root = new TrieNode(); } // Adds a word into the data structure. public void addWord(String word) { TrieNode cur = root; for(char c : word.toCharArray()) { if(cur.trieNode[c - 'a'] == null) cur.trieNode[c - 'a'] = new TrieNode(); cur = cur.trieNode[c - 'a']; } cur.isLast = 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 cur = root; return search(cur, word, 0); } public boolean search(TrieNode cur, String word, int index) { if(cur == null) return false; if(index == word.length()) return cur.isLast; char c = word.charAt(index); if(c == '.') { for(TrieNode node : cur.trieNode) { if(search(node, word, index + 1)) return true; } } else { cur = cur.trieNode[c - 'a']; return search(cur, word, index + 1); } return false; } } // Your WordDictionary object will be instantiated and called as such: // WordDictionary wordDictionary = new WordDictionary(); // wordDictionary.addWord("word"); // wordDictionary.search("pattern");