在python中，我有一个int并想从lis中减去它

Question

在python中：如何将用户从列表中接收到的int除以，而每次它在for循环中运行时，我都需要将在下一轮中之前从该轮接收到的值除以？你知道吗

这是我的密码：

a = input('price: ')
b = input('cash paid: ')
coin_bills = [100, 50, 20, 10, 5, 1, 0.5]
if b >= a:
    for i in coin_bills:
        hef = b - a
        print (hef / i), '*', i
else:
    print 'pay up!'

例如：a=370 b=500 ---> b-a=130
现在在循环中，我将得到（当I=100时）1，当I=50时，我将得到2，但我想在第二轮中（当I=50时）将30除以50。
我需要在代码中更改什么？ 谢谢！你知道吗

Answer 1

你只需要把你在每一步所做的改变减去你在每一步所做的改变。如果将变量名更改为有意义的名称，则更容易查看：

price= int(raw_input('price: ')) # Use int(raw_input()) for safety.
paid= int(raw_input('cash paid: '))
coin_bills=[100,50,20,10,5,1,0.5]
if paid >= price:
    change = paid - price
    for i in coin_bills:
        # Use // to force integer division - not needed in Py2, but good practice
        # This means you can't give change in a size less than the smallest coin!
        print (change // i),'*',i
        change -= (change // i) * i # Subtract what you returned from the total change.
else:
    print 'pay up!'

您还可以通过只打印实际返回的硬币/钞票来清除输出。那么内部循环可能看起来像这样：

for i in coin_bills:
    coins_or_bills_returned = change // i
    if coins_or_bills_returned: # Only print if there's something worth saying.
        print coins_or_bills_returned,'*',i
        change -= coins_or_bills_returned * i