string isBalanced(string s) {
    unordered_map<char, char> map = {
        {'(', ')'},
        {'{', '}'},
        {'[', ']'}
    };
    
    stack<char> sc;
    for (char c : s) {
        if (map.count(c))
            sc.push(map[c]);
        else {
            if (sc.empty() || sc.top() != c)
                return "NO";
            sc.pop();
        }
    }
    
    return (sc.empty()) ? "YES" : "NO";
}