力扣题解-211. 添加与搜索单词

力扣题解-211. 添加与搜索单词 - 数据结构设计

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题目：211. 添加与搜索单词 - 数据结构设计

请你设计一个数据结构，支持添加新单词和查找字符串是否与任何先前添加的字符串匹配。

实现词典类 WordDictionary ：

WordDictionary() 初始化词典对象
void addWord(word) 将 word 添加到数据结构中，之后可以对它进行匹配
bool search(word) 如果数据结构中存在字符串与 word 匹配，则返回 true ；否则，返回 false 。word 中可能包含一些 ‘.’ ，每个 . 都可以表示任何一个字母。

示例：
输入：
[“WordDictionary”,“addWord”,“addWord”,“addWord”,“search”,“search”,“search”,“search”]
[[],[“bad”],[“dad”],[“mad”],[“pad”],[“bad”],[".ad"],[“b…”]]
输出：
[null,null,null,null,false,true,true,true]

解释：
WordDictionary wordDictionary = new WordDictionary();
wordDictionary.addWord(“bad”);
wordDictionary.addWord(“dad”);
wordDictionary.addWord(“mad”);
wordDictionary.search(“pad”); // return False
wordDictionary.search(“bad”); // return True
wordDictionary.search(".ad"); // return True
wordDictionary.search(“b…”); // return True

提示：
1 <= word.length <= 500
addWord 中的 word 由小写英文字母组成
search 中的 word 由 ‘.’ 或小写英文字母组成
最调用多 50000 次 addWord 和 search

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/design-add-and-search-words-data-structure
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

代码

class WordDictionary {class TrieNode {public:bool isEnd;unordered_map<char, TrieNode*> next;TrieNode() {isEnd = false;next.clear();}};public:TrieNode * root;/** Initialize your data structure here. */WordDictionary() {root = new TrieNode();}/** Adds a word into the data structure. */void addWord(string word) {TrieNode* cur = root;for (char c: word) {if (cur->next.count(c) == 0) {cur->next[c] = new TrieNode();}cur = cur->next[c];}cur->isEnd = true;}/** Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter. */bool search(string word) {return find(word, 0, word.length(), root);}bool find(string& word, int start, int end, TrieNode* cur) {if (start == end) {return cur->isEnd;}if (word[start] != '.') {if (cur->next.count(word[start]) == 0) {return false;}return find(word, start+1, end, cur->next[word[start]]);} else {for (auto iter: cur->next) {bool flag = find(word, start+1, end, cur->next[iter.first]);if (flag) {return true;}}return false;}return false;}
};/*** Your WordDictionary object will be instantiated and called as such:* WordDictionary* obj = new WordDictionary();* obj->addWord(word);* bool param_2 = obj->search(word);*/

代码2

前缀树的定义合并到类中。

class WordDictionary {bool isEnd;unordered_map<char, WordDictionary*> next;
public:/** Initialize your data structure here. */WordDictionary() {isEnd = false;}/** Adds a word into the data structure. */void addWord(string word) {WordDictionary* cur = this;for (char c: word) {if (cur->next.count(c) == 0) {cur->next[c] = new WordDictionary();}cur = cur->next[c];}cur->isEnd = true;}/** Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter. */bool search(string word) {return find(word, 0, word.length(), this);}bool find(string& word, int start, int end, WordDictionary* cur) {if (start == end) {return cur->isEnd;}if (word[start] != '.') {if (cur->next.count(word[start]) == 0) {return false;}return find(word, start+1, end, cur->next[word[start]]);} else {for (auto iter: cur->next) {bool flag = find(word, start+1, end, cur->next[iter.first]);if (flag) {return true;}}return false;}return false;}
};/*** Your WordDictionary object will be instantiated and called as such:* WordDictionary* obj = new WordDictionary();* obj->addWord(word);* bool param_2 = obj->search(word);*/