Score of Parenthesis.java

class Solution {
    
    private static final int CONTAINER = 1;
    private static final int BOX = 0;
    
    public int scoreOfParentheses(String S) {
        
        Stack<Integer> data = new Stack<Integer>();
        
        int sum = 0;
        for (int i = 0; i < S.length(); i++) {
            char c = S.charAt(i);
            
            if (c == '(') {
                data.push(S.charAt(i + 1) == ')' ? BOX : CONTAINER);
            } else {
                int type = data.pop();

                if (type == BOX) {
                    sum += Math.pow(2, data.size());
                }
            }
        }
        
        return sum;
    }
}