currencySolver.py

from functools import reduce

def factors(n):
    return set(filter(lambda x:n%x==0, range(1, n+1)))

def solve(a, b, c):
    setA = set() if a%c==0 else reduce(set.union, map(factors,range(a, 1, -c)), set())
    setB = set() if b%c==0 else reduce(set.union, map(factors,range(b, 1, -c)), set())
    if len(setA) == 0 and len(setB) == 0:
        return [-1]
    elif len(setA) == 0:
        return list(setB)
    elif len(setB) == 0:
        return list(setA)
    else:
        return list(setA & setB)

print(solve(3,5,3))
# prints [1,2,5]