recursive function to guess number

[VinceHofman]

Almost everybody knows this game: someone has a number in his head and the other one has to guess what number that is.

The only hints that this person give is: too high or too low.

I'm trying to create a function to find the highest number in a directory. I have a directory with files 001.jpg, 002.jpg, 003.jpg, 004.jpg and so on towards 067.jpg. But i want a function that finds this highest number.

I thought the following algoritm would be nice to use:

Start at 100. Check of 100.jpg exists. If no, divide by 2. Check of 50.jpg exists. If no, divide by 2. But in this case it's YES. So, divide by 2 and sum that(?) 50 + 25 = 75. Check if 75.jpg exists... and so on...

Is there a function already like this or are there other smart functions for this problem

[LordShryku]

Why guess and do the math and all that? Read the directory, strip off the extension, gather numeric names into an array, then [man]sort[/man].

[VinceHofman]

Well, i thought about that but:

if there are 345 files, php has to put al those 345 into an array and sort.

There will be more than 100 000 uniques on the site, so with my algoritm the script only uses a few steps to find the highest(newest) directory. (i said 001.jpg, but it are directories 001, 002, 003 etc. etc.)

[laserlight]

Read up on binary search, since you're effectively doing that.