'''
Author: 365JHWZGo
Description: 860.柠檬水找零
Date: 2021-11-01 09:28:07
FilePath: \Python\test\greedy\greedy-10.py
LastEditTime: 2021-11-01 09:45:41
LastEditors: 365JHWZGo
'''
class Solution(object):
    def lemonadeChange(self, bills):
        """
        :type bills: List[int]
        :rtype: bool
        """
        #当第一笔消费不是5元时无法找零，直接返回False
        if bills[0]!=5:         
            return False
        
        #当第一笔消费为5元时
        num5 = 0    #5元的数量
        num10 = 0   #10元的数量
        # num20 = 0   #20元的数量
        for i in range(len(bills)):
            if bills[i]==5:
                num5+=1
            elif bills[i]==10:
                num10+=1
                num5-=1
            else:
                # num20+=1
                num10-=1
                if num10<0:
                    num10=0
                    num5-=2
                num5-=1
                
            if num5<0 or num10<0:
                return False
        return True