At 06:49 AM 8/6/2007, Kent Johnson wrote:
>Dick Moores wrote:
>>http://www.rcblue.com/Python/changeMaker_revised_for_US_denominations.py
>>I'm still working at Python--been at it a while--and thought the
>>script was ingenious. Do the Tutors agree? Or is it just
>>run-of-the-mill programming? Could it have been more simply written?
>
>I don't find it either ingenious or well-written. The algorithm is
>the same one you would use to count out an amount by hand so it
>doesn't seem so unusual. IMO the code relies too much on indices. If
>you rewrite it using a dict (or, even better, defaultdict(int)) for
>coinCount, there is no need for indices at all. Even with coinCount
>as a list, it could be better written.
>
>coinCount = []
>for d in denominations:
> coinCount.append(0)
>
>=>
>
>coinCount = [0] * ndenominations
>
>
>The main loop could be
>for deno in range(ndenominations):
> if not remaining:
> break
>
>or
>for i, deno in enumerate(denominations):
># i is now the index, deno is the actual denomination
>
>
>but I would write it this way and avoid the use of the index completely:
>
>from collections import defaultdict
>coinCount = defaultdict(int)
>remaining = change
>
># Loop until either we have given all the change or we have
># run out of coin denominations to check.
>for deno in denominations:
> if not remaining:
> break
>
> # For one denomination, count out coins of that denomination
> # as long as the remaining amount is greater than the denomination
> # amount.
>
> while remaining >= deno:
> coinCount[deno] += 1
> print "remaining =", remaining
> remaining -= deno
>
># Report the results.
>print "Your change is $%.02f"% (float(change) / CPD)
>for deno in denominations:
> if coinCount[deno] > 0:
> if deno >= 100:
> print "$%d bills:\t" % (deno / CPD), coinCount[deno]
> else:
> print "%d-cent coins:\t" % (deno), coinCount[deno]
>
>
>Kent
Thanks Kent!
Here's what I have after incorporating your suggestions:
=================================
#!/usr/bin/env python
#coding=utf-8
from collections import defaultdict
CPD = 100
cost = int(CPD * float(raw_input("Enter the cost: ")))
tend = int(CPD * float(raw_input("Enter the tendered amount: ")))
# Calculate the change.
change = tend - cost
coinCount = defaultdict(int)
print coinCount
remaining = change
denominations = (2000, 1000, 500, 100, 50, 25, 10, 5, 1)
# Loop until either we have given all the change or we have
# run out of coin denominations to check.
for deno in denominations:
if not remaining:
break
# For one denomination, count out coins of that denomination
# as long as the remaining amount is greater than the denomination
# amount.
while remaining >= deno:
coinCount[deno] += 1
remaining -= deno
# Report the results.
print "Your change is $%.02f"% (float(change) / CPD)
for deno in denominations:
if coinCount[deno] > 0:
if deno >= 100:
print "$%d bills:\t" % (deno / CPD), coinCount[deno]
else:
print "%d-cent coins:\t" % (deno), coinCount[deno]
========================================
Gotta say though, I still don't understand how the defaultdict works here.
Dick
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