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10:53
Small and nice problem:
An N×N matrix is valid if every column and row contains all integers from 1 to N.
Return true if the matrix is valid
My solution:
{∧/{(⍵[⍋⍵])≡⍳≢⍵}⍤1⊢⍵⍪⍉⍵}
any other ideas?
Making it tacit made it less readable by the way
Was triggered by this one because I saw only 15+ lines solutions in other languages
11:16
∧⌿(⍋⍤⍋≡⊢)¨⍤(,⍥↓∘⍉⍨)
basically check if each wow and column is a permutation
oh, you had a good idea using Rank: ∧⌿(⍋⍤⍋≡⊢)⍤1⍤(⍪∘⍉⍨)
@Richard I believe ∧⌿⍳⍤≢∊⍤1⍪∘⍉⍨ does the trick, or ∧⌿⍋∊⍤1⍪∘⍉⍨ if you're golfing.
I wrote that "in the blind". Does it work?
11:35
would it not return a matrix, so you have to do reduce twice?
or do a ravel before
Ah yes, it should be ∧⌿⍤∊⍤1 rather than just ∊⍤1
Or yes, do ∧⌿⍤, instead of ∧⌿
Shortest (and fastest) would be ~0∊⍋∊⍤1⍪∘⍉⍨
is grade really faster than iota tally?
No, of course not. Fastest will be with ⍳⍤≢
Although, if N is reasonably small, and the matrix is actually valid, then the first column will only have unique small integers. They should be fast to grade.
 
4 hours later…
15:46
tinyapl part 7: Quads, Key, Index released, and with it the latest version of TinyAPL, 0.4.1.0
@Adám cc for apl.news (thanks in advance!)
16:03
@RubenVerg Done.

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