【Codeforces Round #501 (Div. 3)】 A:https://www.cnblogs.com/myx12345/p/9842904.html B:https://www.cnblogs.com/myx12345/p/9842964.html C:https://www.cnblogs.com/myx12345/p/9842977.html D:https://www.cnblogs.com/myx12345/p/9852909.html E:https://www.cnblogs.com/myx12345/p/9932309.html F:https://www.cnblogs.com/myx12345/p/9935872.html