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shaheen_setu
Jul '12

If n = 5 then set {n} = {1,2,3,4,5}. When r = 3 ,i have to compute
sum = 1.2.3 + 1.2.4 + 1.2.5 + 1.3.4 + 1.3.5 + 1.4.5 + 2.3.4 + 2.3.5 + 2.4.5 + 3.4.5 [(.) = (*) multiply sign here].

Is there any closed form formula for arbitrary given (N and R)? plz help with this problem...

Thanks in advance...

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    Jul '12

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    Aug '12
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leppyr64
Jul '12

What's the best solution you have come up with? What input constraints do you expect?

shaheen_setu
Jul '12

I have tried with for loops and that worked for some small constraints. But bro i was curious to find out itz closed form formula. Itz N < 100 and R < 10.

leppyr64
Jul '12

With constraints this small, an O(N*R) should be more than sufficient.

11 days later

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