摘要：
一、题目描述The N cities of Estiah are connected by N-1 roads. The roads are built in a way that it’s always possible to travel between any two cit... 阅读全文
摘要：
一、题目描述We wish to tile a grid 4 units high and N units long with rectangles (dominoes) 2 units by one unit (in either orientation). For exampl... 阅读全文
摘要：
一、题目描述There is a famous railway station in PopPush City. Country there is incredibly hilly. The station was built in last century. Unfortunat... 阅读全文