message: Update lemonade-change.py
diff: # Time: O(n)
  # Space: O(1)
  +import collections
  +
  +
  class Solution(object):
  + def lemonadeChange(self, bills):
  + """
  + :type bills: List[int]
  + :rtype: bool
  + """
  + coins = [20, 10, 5]
  + counts = collections.defaultdict(int)
  + for bill in bills:
  + counts[bill] += 1
  + change = bill - coins[-1]
  + for coin in coins:
  + if change == 0:
  + break
  + if change >= coin:
  + count = min(counts[coin], change//coin)
  + counts[coin] -= count
  + change -= coin * count
  + if change != 0:
  + return False
  + return True
  +
  +
  +class Solution2(object):
  def lemonadeChange(self, bills):
  """
  :type bills: List[int]
  