Car Hidden Inside Cart

bool contains(Node* root, const string& w) {
    Node* cur = root;
    for (char c : w) {
        int i = c - 'a';
        if (!cur->next[i]) return false;
        cur = cur->next[i];
    }
    return cur->childCount == 0;      // "a leaf means a word ended here"
}

The trie is built by inserting "cart" and then "car", and insertion maintains childCount correctly but stores no end-of-word flag. What do contains(root, "car") and contains(root, "cart") return?