Python simple & readable
\nclass Solution:\n    def lemonadeChange(self, bills):\n        five = ten = 0\n        for num in bills:\n            if num == 5:\n                five += 1\
```\nclass Solution:\n    def lemonadeChange(self, bills):\n        five = ten = 0\n        for num in bills:\n            if num == 5:\n                five += 1\n            elif num == 10 and five:\n                ten += 1\n                five -= 1\n            elif num == 20 and five and ten:\n                five -= 1\n                ten -= 1\n            elif num == 20 and five >= 3:\n                five -= 3\n            else:\n                return False\n        return True\n```
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