摘要:
A domino is a flat, thumbsized tile, the face of which is divided into two squares, each left blank or bearing from one to six dots. There is a row of 阅读全文
posted @ 2017-10-16 18:40
Kaiser-
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摘要:
Some major cities have subway systems in the form of a tree, i.e. between any pair of stations, there is one and only one way of going by subway. More 阅读全文
posted @ 2017-10-16 18:36
Kaiser-
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