332. 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:
Input: stones = [2,7,4,1,8,1]
Output: 1

Example 2:
Input: stones = [1]
Output: 1

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