B：https://blog.nowcoder.net/n/24164a5ae97241b8aaa68769b1c21035 D：https://blog.nowcoder.net/n/98e97f73a558473f896cfdbb776c58e8 E：https://blog.nowcoder.net/n/4c6f395bc32e470883c8a78eacd758a9