leetcode 208. Implement Trie (Prefix Tree)

Implement a trie with insert, search, and startsWith methods.
Note:
You may assume that all inputs are consist of lowercase letters a-z.

字典树

class Trie {
public:
    class node {
      public:
        node* next[26];
        int end;
        node() {
            for (int i = 0; i < 26; ++i) {
                next[i] = nullptr;
            }
            end = 0;
        }
    };
    /** Initialize your data structure here. */
    node* root;
    Trie() {
        root = new node();
    }
    
    /** Inserts a word into the trie. */
    void insert(string word) {
        if (word.size() == 0) return ;
        node* p = root;
        for (int i = 0; i < word.size(); ++i) {
            int x = word[i] - 'a';
            if (p->next[x] == nullptr) {
                p->next[x] = new node();
                p = p->next[x];
            } else {
                p = p->next[x];
            }
        }
        p->end = 1;        
    }
    
    /** Returns if the word is in the trie. */
    bool search(string word) {
        node* p = root;
        for (int i = 0; i < word.size(); ++i) {
            int x = word[i] - 'a';
            if (p->next[x] != nullptr) {
                p = p->next[x];
            } else {
                return false;
            }
        }
        if (p->end == 1) return true;
        return false;
    }
    
    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        node* p = root;
        for (int i = 0; i < prefix.size(); ++i) {
            int x = prefix[i] - 'a';
            if (p->next[x] != nullptr) {
                p = p->next[x];
            } else {
                return false;
            }
        }
        return true;
    }
};

/**
 * Your Trie object will be instantiated and called as such:
 * Trie obj = new Trie();
 * obj.insert(word);
 * bool param_2 = obj.search(word);
 * bool param_3 = obj.startsWith(prefix);
 */