CPP - Divisble Subarrays, Pigeonhole Problem

#1

for 3c2 you computed using formula as
(n*(n-1))/2 why? is it the general formula for NcR

#2

Its not the general formula for C(n,r)
For 2 only, it is same as n*(n-1)/2 hence used. Recommended you use the mathematical formula where ever required

#3

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