Problem Statement

Given a string s of '(' and ')' parentheses, we add the minimum number of parentheses ( '(' or ')', and in any positions ) so that the resulting parentheses string is valid.

Formally, a parentheses string is valid if and only if:

• It is the empty string, or
• It can be written as AB (A concatenated with B), where A and B are valid strings, or
• It can be written as (A), where A is a valid string.

Given a parentheses string, return the minimum number of parentheses we must add to make the resulting string valid.

Example 1:

Input:s = "())"
Output:1

Example 2:

Input:s = "((("
Output:3

Example 3:

Input:s = "()"
Output:0

Example 4:

Input:s = "()))(("
Output:4

Note:

1. s.length <= 1000
2. s only consists of '(' and ')' characters.

Problem Link

Minimum Add to Make Parentheses Valid - LeetCode