In England the currency is made up of pound, £, and pence, p, and there are eight coins in general circulation:
1p, 2p, 5p, 10p, 20p, 50p, £1 (100p) and £2 (200p).
It is possible to make £2 in the following way:
1×£1 + 1×50p + 2×20p + 1×5p + 1×2p + 3×1p
How many different ways can £2 be made using any number of coins?
硬币求和
英国的货币单位包括英镑£和便士p，在流通中的硬币一共有八种：
1p, 2p, 5p, 10p, 20p, 50p, £1 (100p), £2 (200p)
以下是组成£2的其中一种可行方式：
1×£1 + 1×50p + 2×20p + 1×5p + 1×2p + 3×1p
不限定使用的硬币数目，组成£2有多少种不同的方式？
coins = [200, 100, 50, 20, 10, 5, 2, 1]
def process(price, coin_table):
result = 0
for coin in coin_table:
times = price / coin
if times:
for t in range(1, times + 1):
leave = price - t * coin
if leave > 0:
result += process(leave,
coin_table[coin_table.index(coin) + 1:])
elif leave == 0:
result += 1
return result
print process(200, coins)
感想：
- 虽然递归是效率最差的，但是我还是用了递归
- 不需要的数据就扔掉