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Minimum Add to Make Parentheses Valid

Problem statement​

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

Constraints:

  • 1 <= s.length <= 1000
  • s[i] is either '(' or ')'.

My solution​

/**
 * @param {string} s
 * @return {number}
 */
var minAddToMakeValid = function(s) {
    const stack = [];
    let count = 0;
    
    for (const char of s.split("")) {
        // console.log(stack)
        if (char === "(") {
            stack.push(char)
        } else if (char === ")" && stack[stack.length - 1] === "(") {
            stack.pop()
        } else {
            count++
        }
    }
    
    return count + stack.length;
};