LeetCode 实现 Trie (前缀树)
题目链接：https://leetcode-cn.com/problems/implement-trie-prefix-tree/
题目大意：
略。
分析：
字典树模板.
代码如下：
1 class Trie { 2 public: 3 int passed; // 记录经过这个节点的字符串数量 4 int ends; // 记录有多少个字符串以这个节点结尾 5 unordered_map< char, Trie* > nxt; 6 7 /** Initialize your data structure here. */ 8 Trie() { 9 passed = 0; 10 ends = 0; 11 } 12 13 /** Inserts a word into the trie. */ 14 void insert(string word) { 15 Trie* p = this; 16 for(int i = 0; i < word.size(); ++i) { 17 if(p->nxt.find(word[i]) == p->nxt.end()) { 18 p->nxt[word[i]] = new Trie(); 19 } 20 ++p->passed; 21 p = p->nxt[word[i]]; 22 } 23 ++p->ends; 24 } 25 26 /** Returns if the word is in the trie. */ 27 bool search(string word) { 28 Trie* p = this; 29 for(int i = 0; i < word.size(); ++i) { 30 if(p->nxt.find(word[i]) == p->nxt.end()) return false; 31 p = p->nxt[word[i]]; 32 } 33 return p->ends != 0; 34 } 35 36 /** Returns if there is any word in the trie that starts with the given prefix. */ 37 bool startsWith(string prefix) { 38 Trie* p = this; 39 for(int i = 0; i < prefix.size(); ++i) { 40 if(p->nxt.find(prefix[i]) == p->nxt.end()) return false; 41 p = p->nxt[prefix[i]]; 42 } 43 return true; 44 } 45 }; 46 47 /** 48 * Your Trie object will be instantiated and called as such: 49 * Trie* obj = new Trie(); 50 * obj->insert(word); 51 * bool param_2 = obj->search(word); 52 * bool param_3 = obj->startsWith(prefix); 53 */
