[LeetCode] Lemonade Change 买柠檬找零

At a lemonade stand, each lemonade costs?$5.?

Customers are standing in a queue to buy from you, and order one at a time (in the order specified by?bills).

Each customer will only buy one lemonade and?pay with either a?$5,?$10, or?$20?bill.? You must provide the correct change to each customer, so that the net transaction is that the customer pays $5.

Note that you don‘t have any change?in hand at first.

Return?true?if and only if you can provide every customer with correct change.

Example 1:

Input: [5,5,5,10,20]
Output: true
Explanation:
From the first 3 customers, we collect three $5 bills in order.
From the fourth customer, we collect a $10 bill and give back a $5.
From the fifth customer, we give a $10 bill and a $5 bill.
Since all customers got correct change, we output true.

Example 2:

Input: [5,5,10]
Output: true

Example 3:

Input: [10,10]
Output: false

Example 4:

Input: [5,5,10,10,20]
Output: false
Explanation:
From the first two customers in order, we collect two $5 bills.
For the next two customers in order, we collect a $10 bill and give back a $5 bill.
For the last customer, we can't give change of $15 back because we only have two $10 bills.
Since not every customer received correct change, the answer is false.

Note:

• 0 <= bills.length <= 10000
• bills[i]?will be either?5,?10, or?20.

参考资料：

https://leetcode.com/problems/lemonade-change/

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[LeetCode] Lemonade Change 买柠檬找零

原文：https://www.cnblogs.com/grandyang/p/10663469.html