On 11/22/2012 03:17 PM, Walter Prins wrote:
Hi Peter,
On 22 November 2012 12:55, Peter O'Doherty <m...@peterodoherty.net
<mailto:m...@peterodoherty.net>> wrote:
Hi list,
Firstly, apologies for the low-level nature of this question -
it's really quite basic but I don't seem to be able to solve it.
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
if x > y and x > z and x%2 != 0:
print 'x is largest and odd'
elif y > x and y > z and y%2 != 0:
print 'y is largest and odd'
elif z > x and z > y and z%2 != 0:
print 'z is largest and odd'
else:
print 'no odd'
The key logical mistake you make is that by your current logic the
*smallest* number can never be the largest odd number, which is
obviously false as in your example.
Break the problem down (divide and conquer). Suppose I gave you only
2 numbers, and you had to say which of the 2 numbers were the largest
odd, what would be the possible outcomes and what would the the
solution be? (Hint, both can be odd, only x can be odd, only y can be
odd, or neither can be odd.) Once you have that answer, then repeat
the exact same solution for the first 2 numbers and apply to the
answer from x&y and and the remaining z. The result from that is
tells you the largest odd number from all 3. (Aside, your question
states to print the largest odd number, which I interpret to mean the
value, not the name of the variable holding the value. )
Walter
Thanks Walter.
This code appears to work although it's very cumbersome. Is there a
better way to do it?
x, y, z = 6, 23, 16
if x%2 != 0 and y%2 !=0:
if x > y:
ans = x
else:
ans = y
elif x%2 !=0 and y%2 == 0:
ans = x
else:
ans = y
if ans%2 != 0 and z%2 !=0:
if ans > z:
ans = ans
else:
ans = z
elif ans%2 !=0 and z%2 == 0:
ans = ans
else:
ans = z
print str(ans) + ' is largest odd'
Regards,
Peter
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