Trie (dynamic allocation)

struct trie{
    trie* child[27];
    trie(){
        for(int i=0;i<27;i++){
            child[i] = NULL;
        }
    }
};

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

    /** Inserts a word into the trie. */
    void insert(string word) {
        trie* cur =  root;
        for(int i=0;i<word.length();i++){
            if((cur->child[word[i]-'a'])==NULL){
                cur->child[word[i]-'a'] = new trie;
            }
            cur = cur->child[word[i]-'a'];
        }
        cur->child[26] = new trie;
    }

    /** Returns if the word is in the trie. */
    bool search(string word) {
        trie* cur =  root;
        for(int i=0;i<word.length();i++){
            if((cur->child[word[i]-'a'])==NULL){
                return false;
            }
            cur = cur->child[word[i]-'a'];
        }
        if( cur->child[26]) return true;
        return false;
    }

    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        trie* cur =  root;
        for(int i=0;i<prefix.length();i++){
            if((cur->child[prefix[i]-'a'])==NULL){
                return false;
            }
            cur = cur->child[prefix[i]-'a'];
        }
        return true;
    }
};