1801. Number of Orders in the Backlog

You are given a 2D integer array orders, where each orders[i] = [pricei, amounti, orderTypei] denotes that amounti orders have been placed of type orderTypei at the price pricei. The orderTypei is: - 0 if it is a batch of buy orders, or - 1 if it is a batch of sell orders. Note that orders[i] represents a batch of amounti independent orders with the same price and order type. All orders rep