Midterm Solutions (Coding)

subsets [] = pp[[
subsets (x:xs) = subsets xs ++ addToEach x (subsets xs)

addToEach x [] = []
addToEach x (xs:xss) = (x:xs) : addToEach x xss

comb _  0 = [[]]
comb [] _ = []
comb (x:xs) n = addToEach x (comb xs (n-1)) ++ comb xs n

primeFactors n = pfHelper n 2

pfHelper n f | n < f = []
         | (mod n f == 0) = f : pfHelper (div n f)
         | otherwise = pfHelper n (f+1)

checkBase n = noDups (primeFactors n)

noDups [x] = True
noDups x:y:xs = (x /= y) && noDups (y:ys)

idiv2 [] = []
idiv2 [x] = []
idiv2 (x:y:xs) = x: idiv2 xs