[Tutor] Simple guessing game - need help with the math

[Dave Angel]

Greg Markham <greg.markham at gmail.com> Wrote in message:

Please post as text. Because you used html, I cannot quote your
 message,  or indeed even see it at all while replying. There are
 other problems frequently triggered by html, but on to my
 response.

You don't specify the python version you're writing for.  I have
 to guess 3.x, since your use of input would have been improper in
 2.x.

Your immediate problem is indeed caused by truncation.  In python
 version 2.x, dividing an int ny 2 will truncate down.   You can
 fix that by using
    change = int ((1 + change)/ 2)

You also need to repeat that in the appropriate elif clause.

You do have other problems,  however,  Your calculation for the
 new guess is wrong in the elif clause.  See if you can spot the
 problem.  Your while loop termination condition will end the loop
 if a user types something other than one of the three valid ones.
 And your logic when the user says 'c' starts the next game
 without reinitializing guess to 50.

Your use of round in the guess= lines is superfluous.  But you may
 need to add 1 here as well. I'd suggest starting change at 100,
 and cutting it in half before adding or subtracting it from the
 guess. 

Incidentally,  once your code is fixed,  it'll converge much
 faster than the other random suggestion. Further,  the binary
 search technique is well worth understanding and mastering.
 

If I were coding this,  then instead of keeping a 'change'
 variable, I'd keep an upperlimit and a lowerlimit one. Start them
 at 0 and 101, and start your loop. Each time through the loop
 your guess would be halfway between the limits. And each time the
 user tells you that you were high or low, you'd adjust the
 upperlimit or lowerlimit respectively. 


-- 
DaveA