Question

Write a function, called numPens that takes one argument, n, and returns True if it is possible to buy a combination of 5, 8 and 24 pack unit in Python.

Answer 1

How much python do you know? Do you know how to make a function? Do you have any code?

Answer 2

Yes I know how to make a function.

Answer 3

This is the exact question
def numPens(n):
"""
n is a non-negative integer

Returns True if some non-negative integer combination of 5, 8 and 24 equals n
Otherwise returns False.
"""

Answer 4

@Syamantak Are you still there?

Answer 5

Yes

Answer 6

I think i might have a solution, but I to be honest with you I have more experience with Java, so i might not be the most optimal one.

Answer 7

Sorry the solution is not right , but nevertheless Thank You !

Answer 8

Do you have some kind of answer to compare against?

Answer 9

No there is no answer to compare against

Answer 10

Do we have to use all three of them or could we use combinations with only one or two of the diffrent packsizes? for example: n = 15 => 3*5 pack

Answer 11

We could use combination of any one any two or all three , we could also take a number twice and a number once

Answer 12

for example a=5,b=8 and c=24 and n can be anything.It must be done like a+b or 2(A+B) OR A+B+C

Answer 13

This is basically a variation of the old McNugget Problem. I am sure you can find lots on this on google. Here is a link to some related math, hope it helps http://www.mathnerds.com/best/mcnuggets/index.aspx

Answer 14

And here is McNuggets in Python, found on google.

def McNuggets(n):
if n == 0:
return True
for i in (6, 9, 20):
if n >= i and McNuggets(n - i):
return True
return False

Answer 15

Slight adaption of my other post for fun.

def McNuggets(sizes,n):
if n == 0:
return True
for i in (sizes):
if n >= i and McNuggets(sizes,n - i):
return True
return False

for i in range(50):
print(i,McNuggets((6,9,20),i))

for i in range(50):
print(i,McNuggets((5,8,24),i))

Answer 16

Lyrae, the only difference in output between the two seems to be at 0, mine shows True and yours shows False. Not sure which would be considered more accurate.

Answer 17

It's probably yours, mine seem to fail at higer values(?)
And also, recursive functions are awesome ;)

Answer 18

Thinking about it, is 0 even considered a possitive integer(?)

Answer 19

I would think no. Something interesting about the second function I posted is you can send it any set of sizes like below with 4 sizes without changing the function..

for i in range(50):
print(i,McNuggets((6,9,25,31),i))

Answer 20

Here're 3 different implementations of the same problem and they all preform equal. Like @msmithhnova said it's probably a slight modification on the McNuggets Problem.

def numPens(n):
i = 0
while i <= n:
j = i;
while j <= n:
k = j
while k <= n:
if k == n:
return True
k += 24
j += 8
i += 5
return False

def numPens(n):
if n == 0:
return True
for i in (5, 8, 24):
if n >= i and numPens(n - i):
return True
return False

def numPens(n):
if n == 0:
return True
elif n < 0:
return False
elif numPens(n - 24) or numPens(n - 8) or numPens(n - 5):
return True
else:
return False