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## Discussion of Problem 1502. Domino Dots

Can anybody explain the example...
Posted by Urrong 7 Aug 2011 03:28
i cant find 12 distinct combinations if N = 2...
i can only think of:
0-0
0-1
0-2
1-1
1-2
2-2
That are only 6 combinations... what did i miss?
Re: Can anybody explain the example...
Posted by skydos 7 Aug 2011 13:54
0-0 (0+0=0)
0-1 (0+1=1)
0-2 (0+2=2)
1-1 (1+1=2)
1-2 (1+2=3)
2-2 (2+2=4)
|
0+1+2+2+3+4=12

got it?
Re: Can anybody explain the example...
Posted by Bogatyr 16 Oct 2012 15:14
The problem does not ask you to count the # of distinct dominoes in a set, it asks you to count the # of dots on a complete set.
Re: Can anybody explain the example...
Posted by Md. Shahedul Islam (Shahed) 12 Jun 2015 03:17
but how does the formula N*(N+1)/2*(N+2) comes ? pls explain... :)