The primary signal is desiredSize on the controller. It can be positive (wants data), zero (at capacity), negative (over capacity), or null (closed). Producers are supposed to check this value and stop enqueueing when it's not positive. But there's nothing enforcing this: controller.enqueue() always succeeds, even when desiredSize is deeply negative.
舞池两侧，专门接待日本客人、手下都是“老虎”的两位“公公”不时在各自的小姐身边逡巡，神情警觉，又有点闷闷不乐。一晚上，偶尔出现的几只“猎物”，也会被他们抢夺分食，而生存最大的资本就是小姐的本事。
，更多细节参见91视频
output[count[idx] - 1] = arr[i]; // 放到正确位置
输入：prices = [8,4,6,2,3]