摘要：
题目链接：点击打开链接 Description The island nation of Flatopia is perfectly flat. Unfortunately, Flatopia has a very poor system of public highways. The Flatop 阅读全文
摘要：
题目链接：点击打开链接 There is a rectangular grid of n rows of m initially-white cells each. Arkady performed a certain number (possibly zero) of operations on 阅读全文