0921. Minimum Add to Make Parentheses Valid

https://leetcode.com/problems/minimum-add-to-make-parentheses-valid

Description

A parentheses string is valid if and only if:

• It is the empty string,

• 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.

You are given a parentheses string s. In one move, you can insert a parenthesis at any position of the string.

• For example, if s = "()))", you can insert an opening parenthesis to be "(**(**)))" or a closing parenthesis to be "())**)**)".

Return the minimum number of moves required to make s 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

Constraints:

• 1 <= s.length <= 1000

• s[i] is either '(' or ')'.

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