80 lines
2.4 KiB
Python
80 lines
2.4 KiB
Python
|
# A set of functions to deal with bags of money.
|
||
|
|
#
|
||
|
|
# JMR 2017
|
||
|
|
|
||
|
|
|
||
|
|
# Face values of coins (in cents):
|
||
|
|
COINS = [200, 100, 50, 20, 10, 5, 2, 1]
|
||
|
|
|
||
|
|
def value(bag):
|
||
|
|
"""Return total amount in a bag."""
|
||
|
|
...
|
||
|
|
|
||
|
|
|
||
|
|
def transfer1coin(bag1, c, bag2):
|
||
|
|
"""Try to transfer one coin of value c from bag1 to bag2.
|
||
|
|
If possible, transfer coin and return True, otherwise return False."""
|
||
|
|
...
|
||
|
|
|
||
|
|
|
||
|
|
def transfer(bag1, amount, bag2):
|
||
|
|
"""Try to transfer an amount from bag1 to bag2.
|
||
|
|
If possible, transfer coins and return True,
|
||
|
|
otherwise, return False and leave bags with same values."""
|
||
|
|
if amount == 0:
|
||
|
|
return True
|
||
|
|
if value(bag1) < amount:
|
||
|
|
return False
|
||
|
|
...
|
||
|
|
|
||
|
|
|
||
|
|
def strbag(bag):
|
||
|
|
"""Return a string representing the contents of a bag."""
|
||
|
|
# You may want to change this to produce a more user-friendly
|
||
|
|
# representation such as "4x200+3x50+1x5+3x1=958".
|
||
|
|
return str(bag)
|
||
|
|
...
|
||
|
|
|
||
|
|
|
||
|
|
def main():
|
||
|
|
# A bag of coins is represented by a dict of {coin: number} items
|
||
|
|
bag1 = {1: 4, 2: 0, 5:1, 10: 0, 20: 5, 50: 4, 100: 2, 200: 1}
|
||
|
|
bag2 = {}
|
||
|
|
|
||
|
|
# Test the value function.
|
||
|
|
assert value({}) == 0
|
||
|
|
assert value({1:7, 5:2, 20:4, 100:1}) == 197
|
||
|
|
|
||
|
|
# Test the strbag function.
|
||
|
|
print( strbag({1:7, 5:2, 20:4, 100:1}) ) # 1x100+4x20+2x5+7x1=197
|
||
|
|
print( strbag({1:7, 5:2, 10:0, 20:4, 100:1}) ) # 1x100+4x20+2x5+7x1=197
|
||
|
|
|
||
|
|
print("bag1:", strbag(bag1)) # bag1: 1x200+2x100+4x50+5x20+1x5+4x1=709
|
||
|
|
print("bag2:", strbag(bag2)) # bag2: =0
|
||
|
|
|
||
|
|
print(transfer1coin(bag1, 10, bag2)) # False!
|
||
|
|
print("bag1:", strbag(bag1)) # bag1: 1x200+2x100+4x50+5x20+1x5+4x1=709
|
||
|
|
print("bag2:", strbag(bag2)) # bag2: =0
|
||
|
|
|
||
|
|
print(transfer1coin(bag1, 20, bag2)) # True
|
||
|
|
print("bag1:", strbag(bag1)) # bag1: 1x200+2x100+4x50+4x20+1x5+4x1=689
|
||
|
|
print("bag2:", strbag(bag2)) # bag2: 1x20=20
|
||
|
|
|
||
|
|
print(transfer1coin(bag1, 20, bag2)) # True
|
||
|
|
print("bag1:", strbag(bag1)) # bag1: 1x200+2x100+4x50+3x20+1x5+4x1=669
|
||
|
|
print("bag2:", strbag(bag2)) # bag2: 2x20=40
|
||
|
|
|
||
|
|
print(transfer(bag1, 157, bag2)) # True (should be easy)
|
||
|
|
print("bag1:", strbag(bag1)) # bag1: 1x200+1x100+3x50+3x20+2x1=512
|
||
|
|
print("bag2:", strbag(bag2)) # bag2: 1x100+1x50+2x20+1x5+2x1=197
|
||
|
|
|
||
|
|
print(transfer(bag1, 60, bag2)) # not easy, but possible...
|
||
|
|
print("bag1:", strbag(bag1))
|
||
|
|
print("bag2:", strbag(bag2))
|
||
|
|
|
||
|
|
return
|
||
|
|
|
||
|
|
if __name__ == "__main__":
|
||
|
|
main()
|
||
|
|
|