1021_Remove_outermost_parentheses

// https://leetcode.com/problems/remove-outermost-parentheses/

// My approach

 public String removeOuterParentheses(String S) {
        Stack<Character> stack = new Stack<Character>();
        char []ch = S.toCharArray();
        int count = 0;
        String ans = "";
        for(int i=0;i<ch.length;i++)
        {
            
            if(ch[i]=='(')
            {
                stack.push(ch[i]);
                if(stack.size()>1)
                ans+=ch[i];
            }
            else
            {
                stack.pop();
                if(stack.size()>=1)
                ans+=ch[i];
            }
        }
        return ans;
    }
    
// SOlution

class Solution {
    public String removeOuterParentheses(String S) {
        StringBuilder s = new StringBuilder();
        int opened = 0;
        for (char c : S.toCharArray()) {
            if (c == '(' && opened++ > 0) s.append(c);
            if (c == ')' && opened-- > 1) s.append(c);
        }
        return s.toString();
    }
    }