Given a list of positive integers c[0...n − 1], and a positive
integer v, decides whether we can use numbers from c[0...n − 1] to
make a sum of v, allowing any particular number in the list to be
used multiple times. Or, mathematically, this means that there
exists non-negative integer coefficients, x0, x1, ..., xn−1, such
that v = x0c[0] + x1c[1] + ...xn−1c[n − 1].
For example, given c[0...3] = {2, 4, 6, 10}, and v = 17,...