程序的其他版本：
def change(C, V, res=None):
res = [] if res is None else res
if len(V) == 0:
return len(res), res
maxx = max(V)
V.remove(maxx)
ans = C//maxx
if ans == 0 and maxx < C :
res += [maxx] * ans
return len(res), res
else:
res += [maxx] * ans
return change(C % maxx, V, res)
print change(48,[1, 5, 10, 25, 50])
print change(30,[25, 10, 2, 3, 1])
(6, [25, 10, 10, 1, 1, 1])
(3, [25, 3, 2])
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