I implemented my code using Trie with array of size 26 but only 2 test cases are passed. Can anyone help?

class TrieNode{
public:
char data;
TrieNode **children;
bool isTerminal;

TrieNode(char data){
    this->data = data;
    children = new TrieNode*[26];

    for(int i = 0; i < 26; i++){
        children[i] = NULL;
    }

    isTerminal = false;
}

};

class Trie{ TrieNode *root;

public:
Trie(){
    root = new TrieNode('\0');
}

void add(TrieNode *root, string word){
    if(word.size() == 0){
        root->isTerminal = true;
        return;
    }

    int index = word[0] - 'a';
    TrieNode *child;

    if(root->children[index] != NULL){
        child = root->children[index];
    }
    else{
        child = new TrieNode(word[0]);
        root->children[index] = child;
        // cout<<root->children[index]->data<<endl;
    }

    add(child, word.substr(1));
}

void add(string word){
    add(root, word);
}

int find(TrieNode *root, string word){

    if(word.size() == 0){
        int counter = 1;

        for(int i = 0; i < 26; i++){
            if(root->children[i] != NULL){
                counter++;
            }
        }
        return counter;
    }

    int index = word[0] - 'a';

    if(root->children[index] != NULL){
        TrieNode *child = root->children[index];
        return find(child, word.substr(1));
    }
    else{
        return 0;
    }

}

int find(string word){
    return find(root, word);
}

};

vector contacts(vector> queries) { vector result; Trie *trie = new Trie();

for (int i=0; i < queries.size(); i++) {

    if (queries[i][0] == "add") {
        trie->add(queries[i][1]);
    }
    else if(queries[i][0] == "find") {
        result.push_back(trie->find(queries[i][1]));
    }
}

return result;

}