（一）已满十四周岁不满十六周岁的；
Every fragment means promises created for read() calls, promises for backpressure coordination, intermediate buffer allocations, and { value, done } result objects — most of which become garbage almost immediately.
，更多细节参见safew官方下载
before accepting. To view this content choose ‘accept and continue’.
int mid = left + (right - left) / 2; // 防止溢出的中点计算
先理解原理：看动图 + 手动模拟小数组