LeetCode题解(1801)：积压订单中的订单总数(Python)

题目：​​原题链接​​（中等）

标签：堆、贪心算法

解法一：

class Solution:
    _MOD = 10 ** 9 + 7

    def getNumberOfBacklogOrders(self, orders: List[List[int]]) -> int:
        buy_heap = []
        sell_heap = []

        for price, amount, order_type in orders:
            if order_type == 0:  # buy:买入
                while amount and sell_heap and sell_heap[0][0] <= price:
                    if sell_heap[0][1] <= amount:
                        amount -= sell_heap[0][1]
                        heapq.heappop(sell_heap)
                    else:
                        sell_heap[0][1] -= amount
                        amount = 0
                if amount:
                    heapq.heappush(buy_heap, [-price, amount])
            else:  # sell:卖出
                while amount and buy_heap and -buy_heap[0][0] >= price:
                    if buy_heap[0][1] <= amount:
                        amount -= buy_heap[0][1]
                        heapq.heappop(buy_heap)
                    else:
                        buy_heap[0][1] -= amount
                        amount = 0
                if amount:
                    heapq.heappush(sell_heap, [price, amount])

        return (sum(amount for price, amount in buy_heap) + sum(amount for price, amount in sell_heap)) % self._MOD