# 1710. Maximum Units on a Truck

<https://leetcode.com/problems/maximum-units-on-a-truck>

## Description

You are assigned to put some amount of boxes onto **one truck**. You are given a 2D array `boxTypes`, where `boxTypes[i] = [numberOfBoxesi, numberOfUnitsPerBoxi]`:

* `numberOfBoxesi` is the number of boxes of type `i`.
* `numberOfUnitsPerBoxi`is the number of units in each box of the type `i`.

You are also given an integer `truckSize`, which is the **maximum** number of **boxes** that can be put on the truck. You can choose any boxes to put on the truck as long as the number of boxes does not exceed `truckSize`.

Return *the **maximum** total number of **units** that can be put on the truck.*

**Example 1:**

```
**Input:** boxTypes = [[1,3],[2,2],[3,1]], truckSize = 4
**Output:** 8
**Explanation:** There are:
- 1 box of the first type that contains 3 units.
- 2 boxes of the second type that contain 2 units each.
- 3 boxes of the third type that contain 1 unit each.
You can take all the boxes of the first and second types, and one box of the third type.
The total number of units will be = (1 * 3) + (2 * 2) + (1 * 1) = 8.
```

**Example 2:**

```
**Input:** boxTypes = [[5,10],[2,5],[4,7],[3,9]], truckSize = 10
**Output:** 91
```

**Constraints:**

* `1 <= boxTypes.length <= 1000`
* `1 <= numberOfBoxesi, numberOfUnitsPerBoxi <= 1000`
* `1 <= truckSize <= 106`

## ac

```java
```