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Prime Distance On Tree Problem description. You are given a tree. If we select 2 distinct nodes uniformly at random, what's the probability that the d 阅读全文
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E -- Expected value of the expression E -- Expected value of the expression DESCRIPTION You are given an expression: A0O1A1O2A2⋯OnAnA0O1A1O2A2⋯OnAn, w 阅读全文
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Arithmetic Progressions Given N integers A1, A2, …. AN, Dexter wants to know how many ways he can choose three numbers such that they are three consec 阅读全文