Leetcode Solutions: 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.

class Solution(object):
    def lastStoneWeight(self, stones):
        """
        :type stones: List[int]
        :rtype: int
        """

        stones = [-stone for stone in stones]

        heapq.heapify(stones)


        while len(stones) > 1:
            first  = heapq.heappop(stones)
            second = heapq.heappop(stones)

            if second > first:
                heapq.heappush(stones, first-second)


        return -stones[0] if len(stones) else 0