LeetCode-678.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].

    public boolean checkValidString(String s) {
        int l =0;
        for(int i=0;i<s.length();i++){
            if(s.charAt(i)=='('||s.charAt(i)=='*'){
                l++;
            }
            else{
                l--;
            }
            if(l<0){
                return false;
            }
        }
        if(l==0){
            return true;
        }
        int r =0;
        for(int i=s.length()-1;i>=0;i--){
            if(s.charAt(i)==')'||s.charAt(i)=='*'){
                r++;
            }
            else{
                r--;
            }
            if(r<0){
                return false;
            }
        }
        return true;
    }