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D. Acyclic Organic Compounds You are given a tree T with n vertices (numbered 1 through n) and a letter in each vertex. The tree is rooted at vertex 1 阅读全文
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D. Fools and Foolproof Roads You must have heard all about the Foolland on your Geography lessons. Specifically, you must know that federal structure 阅读全文
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B2. Shave Beaver! The Smart Beaver has recently designed and built an innovative nanotechnologic all-purpose beaver mass shaving machine, "Beavershave 阅读全文