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 becomes [2,4,1,1,1].
We combine 2 and 4 to get 2, so the array becomes [2,1,1,1].
We combine 2 and 1 to get 1, so the array becomes [1,1,1].
We combine 1 and 1 to get 0, so the array becomes [1].
The last remaining stone has weight 1.

Example 2:

Input: stones = [1]
Output: 1
Explanation: There is only one stone, so it is the last remaining stone.