Last Stone Weight

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 the **heaviest two stones** and smash them together. Suppose the heaviest two 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 weight of the last remaining stone_. If there are no stones left, return `0`.   **Example 1:** **Input:** stones = [2,7,4,1,8,1] **Output:** 1 **Explanation:** We combine 7 and 8 to get 1 so the array converts to [2,4,1,1,1] then, we combine 2 and 4 to get 2 so the array converts to [2,1,1,1] then, we combine 2 and 1 to get 1 so the array converts to [1,1,1] then, we combine 1 and 1 to get 0 so the array converts to [1] then that's the value of the last stone. ``` **Example 2:** **Input:** stones = [1] **Output:** 1 ```   **Constraints:** - `1 <= stones.length <= 30` - `1 <= stones[i] <= 1000`