EDIT 2: This code is outdated. The final version is in a later post in this topic.

This is what I've been working on all day. It isn't completely finished; I realized just a few minutes ago that I totally forgot to handle a tied game, and it doesn't give you any fancy victory message when you win. And you will win, since the AI opponent is just "choose a random column." But I didn't make this for the AI; I made it for everything else.

The main program is MAINLOOP (obviously) and I made GRAVITY a subprogram because it saves a few bytes. That brings me to the main reason I made this topic... I want to see if this can be optimized any more than it already is. I think I've already done a decent enough job on it, but I really want to make it as small as it can be.

I've attached both programs, and here's the code too:

MAINLOOP
:Disp "WILL YOU MOVE
:Input "FIRST? Y/N: ",Str1
:Str1≠"Y→T
:{6,7→dim([A]
:Fill 0,[A]
:ClrHome
:For(A,2,7
:Output(A,2,". . . . . . .
:End
:Output(8,2,"-------------
:Repeat W
:If T
:Then
:Repeat not([A](1,Ans
:randInt(1,7→C
:End
:prgmGRAVITY
:Else
:DelVar M4→C
:Repeat M
:Output(1,2C,"V
:Repeat max(K={21,24,26,45
:getKey→K
:End
:If K=45
:Return
:If K=21 and not([A](1,C
:Then
:prgmGRAVITY
:1→M
:Output(1,2C,"
:End
:If K≠21
:Then
:Output(1,2C,"
:C-25+Ans→C
:Ans-7(Ans=8)+7not(Ans→C
:End
:End
:End
:{1,1,1,1→{L1}
:T+1→T
:1→A
:While A<4 and R+A≤6 and Ans
:If T=[A](R+A,C
:Then
:1+{L1}(1→{L1}(1
:A+1→A
:Else
:0
:End
:End
:1→A
:While A<4 and C-A≥1 and Ans
:If T=[A](R,C-A
:Then
:1+{L1}(2→{L1}(2
:A+1→A
:Else
:0
:End
:End
:1→A
:While A<4 and C+A≤7 and Ans
:If T=[A](R,C+A
:Then
:1+{L1}(2→{L1}(2
:A+1→A
:Else
:0
:End
:End
:1→A
:While A<4 and R+A≤6 and C+A≤7 and Ans
:If T=[A](R+A,C+A
:Then
:1+{L1}(3→{L1}(3
:A+1→A
:Else
:0
:End
:End
:1→A
:While A<4 and R-A≥1 and C-A≥1 and Ans
:If T=[A](R-A,C-A
:Then
:1+{L1}(3→{L1}(3
:A+1→A
:Else
:0
:End
:End
:1→A
:While A<4 and R+A≤6 and C-A≥1 and Ans
:If T=[A](R+A,C-A
:Then
:1+{L1}(4→{L1}(4
:A+1→A
:Else
:0
:End
:End
:1→A
:While A<4 and R-A≥1 and C+A≤7 and Ans
:If T=[A](R-A,C+A
:Then
:1+{L1}(4→{L1}(4
:A+1→A
:Else
:0
:End
:End
:max(3<{L1}→W
:not(T-1→T
:End

GRAVITY
:DelVar  RR
:Repeat Ans=5 or [A](Ans+1,C
:Ans+1
:End
:Ans+(Ans=5 and not([A](6,C→R
:T+1→[A](Ans,C
:Output(R+1,2C,sub("XO",T+1,1
In particular, I'm wondering if there's a less ridiculous way of figuring out when a player wins (which is the section in MAINLOOP from the :{1,1,1,1→{L1} line to the :max(3<{L1}→W line). And I know I could already save a few bytes in that section by incrementing T for its duration. But what else? I've hit my limit already

EDIT: I did that T+1→T optimization and saved six bytes. And it also made me catch a bug I didn't even know was there. I've updated the attached file with this fix too.

Cool to hear you're starting coding ^^

Also good idea to start with smaller projects too (like Connect 4), some people usually start with a massive RPG or platformer .

Unfortunately I am not as good for optimizing and reading people code, so it migth be better someone else check the code for deepest optimizations.

I'll give it a try later, though.

I'm ok at some, but that requires me to have the time to sit and read through the code. And unfortunatly I just saw this right as I decided it was too late for me to be up, so I'll have to wait until tomorrow before diving into this.

Edit: hmm, I took a quick peek, and isn't there a way to add all the columns of a matrix? Or is it rows? That could help for checking for a win.

Well I'm pretty good at optimizing my own code, but it's not so easy for me to optimize other peoples code.
I do consider myself an ok optimizer though.

There's cumSum( for finding the cumulative sum of a matrix's columns, but that can't really help me at all, not the way I'm currently storing the grid. Plus, it would only do anything useful for the downwards victory.
The fact that you can win diagonally is what makes this so hard to make more efficient, I think.

That looks very nice!  I think the check code is as optimized as it can get in its current state.  You could probably do something tricky to get it smaller, but I'm not sure what you would have to do.  It looks great!  Great job!

cool I'll update the file on my computer. I didn't got time to try the other version because of work and I was busy messing with my Nspire and Axe. Hopefully I should be able to test later (and maybe do a screenshot)

I'd love to take a look at your AI, especially if it can help me optimize my win-checking code, which it sounds like it can