Valid Parenthesis String

Given a string containing only three types of characters: '(', ')' and '*', write a function to check whether this string is valid. We define the validity of a string by these rules:

1. Any left parenthesis '(' must have a corresponding right parenthesis ')'.
2. Any right parenthesis ')' must have a corresponding left parenthesis '('.
3. Left parenthesis '(' must go before the corresponding right parenthesis ')'.
4. '*' could be treated as a single right parenthesis ')' or a single left parenthesis '(' or an empty string.
5. An empty string is also valid.

Example 1:

Input: "()"
Output: True

Example 2:

Input: "(*)"
Output: True

Example 3:

Input: "(*))"
Output: True

Note:

1. The string size will be in the range [1, 100].

 class Solution {
    public boolean checkValidString(String s) {
       int left = 0, rem = 0;
       for (char ch: s.toCharArray()) {
           left += ch == '(' ? 1 : -1;
           rem += ch != ')' ? 1 : -1;
           if (rem < 0) break;
           left = Math.max(left, 0);
       }
       return left == 0;
    }
}



Try it on Leetcode 

Calculate left parenthesis and also right parenthesis and star separately. If others are lesser than 0 then break. Else if left is negative then bring it up to 0.