class Solution {
 public:
  int bestClosingTime(string customers) {
    // Instead of computing the minimum penalty, we can compute the max profit.
    int ans = 0;
    int profit = 0;
    int maxProfit = 0;

    for (int i = 0; i < customers.length(); ++i) {
      profit += customers[i] == 'Y' ? 1 : -1;
      if (profit > maxProfit) {
        maxProfit = profit;
        ans = i + 1;
      }
    }

    return ans;
  }
};