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# 1049. Last Stone Weight II

<https://leetcode.com/problems/last-stone-weight-ii>

## Description

You are given an array of integers `stones` where `stones[i]` is the weight of the `ith` stone.

We are playing a game with the stones. On each turn, we choose any two stones and smash them together. Suppose the stones have weights `x` and `y` with `x <= y`. The result of this smash is:

* If `x == y`, both stones are destroyed, and
* If `x != y`, the stone of weight `x` is destroyed, and the stone of weight `y` has new weight `y - x`.

At the end of the game, there is **at most one** stone left.

Return *the smallest possible weight of the left stone*. If there are no stones left, return `0`.

**Example 1:**

```
**Input:** stones = [2,7,4,1,8,1]
**Output:** 1
**Explanation:**
We can combine 2 and 4 to get 2, so the array converts to [2,7,1,8,1] then,
we can combine 7 and 8 to get 1, so the array converts to [2,1,1,1] then,
we can combine 2 and 1 to get 1, so the array converts to [1,1,1] then,
we can combine 1 and 1 to get 0, so the array converts to [1], then that's the optimal value.
```

**Example 2:**

```
**Input:** stones = [31,26,33,21,40]
**Output:** 5
```

**Example 3:**

```
**Input:** stones = [1,2]
**Output:** 1
```

**Constraints:**

* `1 <= stones.length <= 30`
* `1 <= stones[i] <= 100`

## ac

```java
```