> For the complete documentation index, see [llms.txt](https://jaywin.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jaywin.gitbook.io/leetcode/solutions/0860-lemonade-change.md).

# 0860. Lemonade Change

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

## Description

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.

Given an integer array `bills` where `bills[i]` is the bill the `ith` customer pays, return `true` *if you can provide every customer with correct change, or* `false` *otherwise*.

**Example 1:**

```
**Input:** bills = [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:** bills = [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 not give change of $15 back because we only have two $10 bills.
Since not every customer received correct change, the answer is false.
```

**Example 3:**

```
**Input:** bills = [5,5,10]
**Output:** true
```

**Example 4:**

```
**Input:** bills = [10,10]
**Output:** false
```

**Constraints:**

* `1 <= bills.length <= 105`
* `bills[i]` is either `5`, `10`, or `20`.

## ac

```java
```