@Sherlock9 Cool. You might also want to "stop him" in the middle and experiment yourself: Go to tryapl.org > Learn > Interesting Explorations > Sudoku Solver
@Adám No I was pausing too. I sort of meant "I don't think I understood even as I typed it" XD I'm still on the line between understanding what's happening and understanding why we're doing it that way and how to apply it elsewhere
box ← {⍵⌿⍵/⍵ ⍵⍴⍳⍵×⍵}
rcb ← {(⍳⍵),¨box⊃⍵*÷2}
⍝ For rcb, why do we need the first element ⊃ of the square root ⍵*÷2?
@Adám You can evaluate a single line of APL by typing it into chat prefixed by ⍞←. Use ⎕← instead for boxed display and multi-line results and use ⋄ instead to silence the first statement. Use ] to call user commands, including ]help ⍣ for help on a glyph etc. Do not use markdown, but fixed-width (4 initial spaces) is fine. Commands: )lb for language bar, )docs for full documentation, )ref for PDF reference card, )idioms for idiom list.