Today I have done leetcode's October LeetCoding Challenge with cpp.

October LeetCoding Challenge 9

Description

Minimum Add to Make Parentheses Valid

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 ')'.

Solution

class Solution {
public:
  int minAddToMakeValid(string s) {
    int answer = 0;
    int count = 0;
    for(auto c : s) {
      if(c == '(') {
        count += 1;
      } else {
        if(!count) {
          answer += 1;
        } else {
          count -= 1;
        }
      }
    }
    answer += count;
    return answer;
  }
};