message: Update lemonade-change.cpp
diff: // Space: O(1)
  class Solution {
  +public:
  + bool lemonadeChange(vector<int>& bills) {
  + static const vector<int> coins = {20, 10, 5};
  + unordered_map<int, int> counts;
  + for (const auto& bill : bills) {
  + ++counts[bill];
  + auto change = bill - coins.back();
  + for (const auto& coin : coins) {
  + if (change == 0) {
  + break;
  + }
  + if (change >= coin) {
  + const auto count = min(counts[coin], change / coin);
  + counts[coin] -= count;
  + change -= coin * count;
  + }
  + }
  + if (change != 0) {
  + return false;
  + }
  + }
  + return true;
  + }
  +};
  +
  +class Solution2 {
  public:
  bool lemonadeChange(vector<int>& bills) {
  int five = 0, ten = 0;
  