# LeetCode 921. Minimum Add to Make Parentheses Valid

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

## 題目大意

如題

## 思考

這題就考很簡單的 balancing count

class Solution
{
public:
    int minAddToMakeValid(string s)
    {
        int l = 0, r = 0;

        for (const char &c : s)
        {
            if (c == '(')
                ++l;
            else
            {
                if (l > 0)
                    --l;
                else
                    ++r;
            }
        }

        return l + r;
    }
};