알고리즘 파트-2 : 대괄호 검증

{([])}    : Valid
{(}}      : Invalid
{(}       : Invalid
{         : Invalid
}         : Invalid
{([)]}    : Invalid 

 public boolean validBrackets(String brackets) {
        char[] arr = brackets.toCharArray();

        Stack<Character> stack = new Stack<>();
        for (Character ch : arr) {
            if (ch == '(' || ch == '{' || ch == '[') {
                stack.push(ch);
            } else {
                if (stack.isEmpty()) {
                    return false;
                } else {
                    if (
                       ch == ')' && stack.peek() == '(' || 
                       ch == '}' && stack.peek() == '{' || 
                       ch == ']' && stack.peek() == '['
                      ){
                        stack.pop();
                    }else{
                        return false;
                    }
                }
            }

        }
        return stack.isEmpty();
    }