Newb ??

[Norman Silverstone]

On Fri, 11 Nov 2005 01:39:40 +1100, Steven D'Aprano wrote:

> On Thu, 10 Nov 2005 13:30:05 +0000, Norman Silverstone wrote:
> 
>>> In that case, think of "bisection".  Originally, all the computer knows
>>> is that the number is in some range, say 0 to 100.  It can then guess
>>> the midpoint, 50.  If it's right, yay!  Otherwise: if it's told to go
>>> lower, then the range is now 0 to 49 -- if higher, it's 51 to 100; in
>>> each case the range was just halved (actually, a bit more than halved).
>> 
>> Thank you, I thought that might be the case. So, I will have to settle
>> down and try to write some pseudo-code first. I hope to be back.
> 
> Heh, you will find that Python is practically executable pseudo-code!
> 
> Untested:
> 
> 
> def guess_number():
>     # please don't cheat the poor computer...
>     print "Guess a number."
>     lo = 0
>     hi = 100
>     while True:
>         guess = (lo+hi)//2
>         ans = raw_input("Is it %d? y/n " % guess)
>         if ans in ('y', 'yes'):
>             break
>         ans = raw_input("Too high? y/n ")
>         if ans in ("y", "yes"):
>             hi = guess-1
>         else:
>             lo = guess+1
> 
> This should run, and it will *almost* do what you want.

Thanks for that but I think it is too simplistic. It appears OK for the
first guess, which is 50 but, what about the next guess. If the guess is
too high then the next guess has to be 50/2. However, if it is too low
then the next guess must be first guess + (100-second guess)/2. In general
terms, if guess is too high then next guess must (guess - lowest
possible)/2 and if too  low then it is guess + (highest possible -
guess)/2. 

Comments please.

Norman