LeetCode 208. 實現 Trie (前綴樹)字典樹（前綴樹、Trie）

實現 Trie
具體地可以看這篇博客：
字典樹入門
版本1：

class Trie {
public:
    /** Initialize your data structure here. */
    Trie() {
        root = new Node;
    }

    ~Trie(){
        queue<Node*> q;
        q.push(root);
        while(!q.empty()){
            Node* pn = q.front();
            q.pop();
            for(unordered_map<char,Node*>::iterator it=pn->childs.begin(); it!=pn->childs.end();it++ ){
                q.push(it->second);
            }
            delete pn;
            pn = nullptr;
        }
    }
    
    /** Inserts a word into the trie. */
    void insert(string word) {
        Node* p = root;
        for(char c:word){
            if(!p->childs.count(c)){
                p->childs[c] = new Node;
            }
            p = p->childs[c];
        }
        p->isEnd = true;
    }
    
    /** Returns if the word is in the trie. */
    bool search(string word) {
        Node* p = root;
        for(char c:word){
            if(!p->childs.count(c)){
                return false;
            }
            p = p->childs[c];
        }
        return p->isEnd;
    }
    
    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        Node* p = root;
        for(char c:prefix){
            if(!p->childs.count(c)){
                return false;
            }
            p = p->childs[c];
        }
        return true;
    }
private:
    struct Node{
        bool isEnd = false;
        unordered_map<char,Node*> childs;
    };
    Node * root;    
};

版本2：

class Trie {
public:
    /** Initialize your data structure here. */
    Trie() {
        root = new TrieNode;
    }
    
    ~Trie(){
        destroy(root);
    }

    /** Inserts a word into the trie. */
    void insert(string word) {
        TrieNode *p = root;
        for(char c:word){
            if(p->childs[c-'a'] == nullptr){
                p->childs[c-'a'] = new TrieNode;
            }
            p = p->childs[c-'a'];
        }
        p->isEnd = true;
    }
    
    /** Returns if the word is in the trie. */
    bool search(string word) {
        TrieNode *p = root;
        for(char c:word){
            if(p->childs[c-'a']==nullptr){
                return false;
            }
            p = p->childs[c-'a'];
        }
        return p->isEnd;
    }
    
    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        TrieNode *p = root;
        for(char c:prefix){
            if(p->childs[c-'a']==nullptr){
                return false;
            }
            p = p->childs[c-'a'];
        }
        return true;
    }
private:
    struct TrieNode{    
        bool isEnd = false;
        TrieNode* childs[26] = {0};
    };
    TrieNode* root ;
    void destroy(TrieNode* root){
        if(!root){
            return ;
        }
        for(TrieNode* pt:root->childs){
            destroy(pt);
        }
        if(root){
            delete root;
            root = nullptr;
        }
    }    
};

偷偷吐槽一句，爲什麼這麼多人寫c++只管new,不管delete呢？