message: Update minimum-remove-to-make-valid-parentheses.cpp
diff: class Solution {
  public:
  string minRemoveToMakeValid(string s) {
  - unordered_set<int> lookup;
  int count = 0;
  for (auto i = 0; i < s.size(); ++i) {
  if (s[i] == '(') {
  