实现trie

class  {
public:
    
    Trie* next[26] = {NULL};
    bool isLeaf;
    Trie() {
        isLeaf = false;
    }
    
    /** Inserts a word into the trie. */
    void insert(string word) {
        Trie* node = this;
        for (char c : word) {
            int i = int(c - 'a');
            if (node->next[i] == NULL) {
                node->next[i] = new Trie();
            }
            node = node->next[i];
        }
        node->isLeaf = true;
        return;
    }
    
    /** Returns if the word is in the trie. */
    bool search(string word) {
        Trie* node = this;
        for (char c : word) {
            int i = int(c - 'a');
            if (node->next[i]) {
                node = node->next[i];
            } else {
                return 0;
            }
        }                      
        if (node->isLeaf) {
            return 1;
        }
        return 0;
    }
    
    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        Trie* node = this;
        for (char c : prefix) {
            int i = int(c - 'a');
            if (node->next[i]) {
                node = node->next[i];
            } else {
                return 0;
            }
        }
     
        return 1;
    }           
};