Discussion @ 1502. Domino Dots @ Timus Online Judge

PrankMaN My formula [2] // Problem 1502. Domino Dots 23 Aug 2011 18:25

Answer for n is n*(n+1)/2*(n+2)

For example if n=2 then answer is 2*3/2*4=12

Soucup Adrian Re: My formula [1] // Problem 1502. Domino Dots 3 Feb 2012 17:24

The formula is correct and is easily proven by solving the sums:

sum(i=0 -> N) sum(j=0 -> N) (i + j)

Edited by author 03.02.2012 17:25

Bogatyr Re: My formula // Problem 1502. Domino Dots 16 Oct 2012 15:22

Actually the inner sum needs to start at i, not at zero. Starting at 0 counts non-double dominoes twice.

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