[Tutor] Beginner's question

[Dave Angel]

On 11/22/2012 10:14 AM, Joel Goldstick wrote:

>> > Peter O'Doherty wrote:
>>> > >
>>> < snip >
>>> > > I need to write a program that examines 3 variables x, y, z, and prints
>>> > > the largest odd number. I've tried all sorts of variations and this is
>>> > > the current version:
>>> > >
>     x, y, z = 26, 15, 20
>
>     largest = None
>     if x %2:
>          largest = x
>     if y % 2:
>          if y > largest:
>               largest = y
>     if z % 2:
>          if z > largest:
>               largest = z;
>
>    if Largest:
>          print "largest value is", largest
>    else:
>          print "no odd values"
>

This one first gets into trouble if x is even and y is odd, because if
tries to compare y with None, which is basically an undefined ordered
comparison (and illegal in Python3, I believe).  The flag value needs to
be an int, or at least numeric.

How about:

x, y, z = 26, 15, 20

if x%2 == y%2 == z%2 == 0:
    print "No odd values"
else:
    if x%2==0: x = y
    if x%2==0: x = y  #now x is odd
    if y%2==0: y = x
    if z%2==0: z = x
    #at this point, they're all odd and we just want the largest one
    if x < y: x, y = y,x
    if x < z: x = z
    print "largest odd value is", x
   

With the caveat that x, y, and z may get modified on their way through. 
I doubt if that really violates the problem statement, however.

I didn't test this with all 120 cases, just with the data supplied.




-- 

DaveA