【全網首發】2021USAJMO 真題及答案 文末有答案 Problem 1 Let??denote the set of positive integers. Find all functions??such that for positive integers??and? Problem 2 Rectangles???and??are erected ou...
【全網首發】2021AIME II 真題及答案 文末答案 Problem 1 Find the arithmetic mean of all the three-digit palindromes. (Recall that a palindrome is a number that reads the same forward and backward, su...