Expectation Value Problem.

Правка en1, от shubhamgoyal__, 2016-08-04 15:37:13

Can somebody please help me out in this problem https://www.codechef.com/CDWR2014/problems/CW2/ My approach: Consider any number i.We can calculate its contribution in final sum.There are n-i numbers bigger than i.We choose any j of them and arrange them before i and rest (n-j-1) numbers are arranged after i. Thus the formula: This sum can then be divided by n!. I saw a few AC codes and somehow people have reduced it to sum of harmonic series,however Im not able to reduce my formula further. Can somebody please help!!.

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en1 Английский shubhamgoyal__ 2016-08-04 15:37:13 633 Initial revision (published)