剑不飞

摘要： Magic SquaresIOI'96 Following the success of the magic cube, Mr. Rubik invented its planar version, called magic squares. This is a sheet composed of 8 equal-sized squares:12348765In this task we consider the version where each square has a different color. Colors are denoted by the first 8 posi 阅读全文

摘要： Feed Ratios1998 ACM Finals, Dan Adkins Farmer John feeds his cows only the finest mixture of cow food, which has three components: Barley, Oats, and Wheat. While he knows the precise mixture of these easily mixable grains, he can not buy that mixture! He buys three other mixtures of the three grains 阅读全文