Can such a program be written?
Yes  100%  [ 9 ]
No  0%  [ 0 ]

Collatz Conjecture

[Pick a number ~ if it is odd, then [*3, +1]. If it is even, then [Divide by 2]. Keep doing this. You will eventually reach a 4-2-1 loop.]

Picture a chart with 0-100 on the bottom & 0-100 on the left side. The bottom row will be for the starting number. The left side will be for the highest number reached before dropping to the 4-2-1 Loop for that starting number. Can such a program be written?

Someone asked what language I wanted. I am not sure of the language, but I wuld like to program it into my TI-~83 Plus.
What makes you think such a program couldn't be written? I don't see anything crazy going on here.
Edit: I made the program both for the number of iterations and for the max value reached.

Code:
```#include <stdlib.h> #include <graphx.h> #include <tice.h> int main(void) {     int num, max, iterations = 0;     char title1[] = "Collatz Iterations";     char title2[] = "Collatz Max Value";     gfx_Begin();     //setup     gfx_SetDrawScreen();     gfx_ZeroScreen();     gfx_SetColor(255);     gfx_SetTextFGColor(255);     gfx_SetTextBGColor(5);     gfx_SetTextTransparentColor(5);     gfx_SetTextScale(2,2);     gfx_PrintStringXY(title1,(LCD_WIDTH - gfx_GetStringWidth(title1)) / 2, 3);     for (int i=1;i<LCD_WIDTH - 1;i++){         num = i;         iterations = 1;         do{             if(num % 2 == 0){                 num = num / 2;             } else {                 num = num * 3 + 1;             }             iterations++;         } while (num != 4);         gfx_FillRectangle_NoClip(i, LCD_HEIGHT - iterations, 2, 2);     }     while (!os_GetCSC());     gfx_ZeroScreen();     gfx_PrintStringXY(title2,(LCD_WIDTH - gfx_GetStringWidth(title2)) / 2, 3);     for (int i=1;i<LCD_WIDTH - 1;i++){         num = i;         max = 1;         do{             if(num % 2 == 0){                 num = num / 2;             } else {                 num = num * 3 + 1;             }             if (max < num){                 max = num;             }         } while (num != 4);         gfx_FillRectangle_NoClip(i, LCD_HEIGHT - (max / 55) , 2, 2);     }     while (!os_GetCSC());     gfx_End();     return 0; } ```
Yes, that's a relatively easy program. Without actually making it show a table, you could throw it together like this:

Code:
```Input "STARTING NUMBER:",X Repeat getKey    If remainder(X,2):Then       3X+1->X    Else       .5X->X    End    Disp X End```

You can stop this version by pressing any key. You could also store the three most recent values in a list and stop when the last three are [4, 2, 1].

Code:
```def callitz():   def cg(n):     yield n     while n != 1:       n = 3 * n + 1 if n % 2 else n // 2       yield n   for n in range(1, 101):     print(n, max(list(cg(n))) ```

You didn't specify a language, but the bottom line is that it is definitely possible (as womp said, why wouldn't it be?).

Also, 0 as a starting point is invalid as posed, since 0 never reaches the 4-2-1 loop. Note additionally that many values <100 reach a rather large maximum.

Edit: thought I'd golf this in TI-BASIC, cause that's what we do here after all.
Display code could be adjusted as desired; current form is 50 49 bytes.

Code:
```:For(I,1,|E2 :I->M :While ln(Ans :.5Ans :If fPart(Ans:6Ans+1 :If Ans>M:Ans->M :End :Disp toString(I :Pause M :End ```
For what it's worth, :While Ans!=1 -> :While Ans-1.
KermMartian wrote:
For what it's worth, :While Ans!=1 -> :While Ans-1.

That doesn't offer any size benefits, correct? Both ≠ and - are single byte tokens, so is there any reason to use - besides being easier to type?

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