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| author | Marshall Lochbaum <mwlochbaum@gmail.com> | 2020-10-18 13:16:09 -0400 |
|---|---|---|
| committer | Marshall Lochbaum <mwlochbaum@gmail.com> | 2020-10-18 13:16:09 -0400 |
| commit | d7d5c92da88b05871fd1fcdee06a9e0edf0c0604 (patch) | |
| tree | 464b7c4a89fb164d5a7f212c4febd2a5d60de2b2 /examples | |
| parent | d88cda4278f2deffeb059c396bbf3872e9d9fef1 (diff) | |
Set inverses for permutation/combination index functions
Diffstat (limited to 'examples')
| -rw-r--r-- | examples/fifty.bqn | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/examples/fifty.bqn b/examples/fifty.bqn index 32deb633..2a9cf317 100644 --- a/examples/fifty.bqn +++ b/examples/fifty.bqn @@ -105,13 +105,15 @@ InversePermutation ← ⍋ # Or ⊐⟜(↕≠) or ∾∘⊔ IndexFromPermutation‿PermutationFromIndex ← { Rfd ← ⊢+´∘>¨¯1↓↓ Dfr ← (⍋∘⍋∾)´ - Ifp ← {⌽×`1+»↕≠𝕩} +´∘× Rfd - Pfi ← Dfr (1+↕)⊸(⌽⊣|¯1↓·⌊∘÷`∾˜) + Ifp ← {𝕊⁼:𝕨Pfi𝕩; (⌽×`1+»↕≠𝕩) +´∘× Rfd𝕩} + Pfi ← {𝕊⁼:𝕨Ifp𝕩; w𝕊𝕩: Dfr (1+↕w) (⌽⊣|¯1↓·⌊∘÷`∾˜) 𝕩} Ifp‿Pfi } ! { p ← 1‿3‿0‿7‿6‿5‿4‿9‿8‿2 - p ≡ 10 PermutationFromIndex IndexFromPermutation p + p ≡ 10 PermutationFromIndex i ← IndexFromPermutation p + p ≡ ⊢⌾(10⊸IndexFromPermutation) p + i ≡ ⊢⌾(10⊸PermutationFromIndex) i } # 22 @@ -121,10 +123,15 @@ Combinations ← {𝕨(=∨0=⊣)◶⟨(0∾˘𝕊⌾(-⟜1))∾1+𝕊⟜(-⟜1) # 23 IndexFromCombination‿CombinationFromIndex ← { C ← ((-˜+↕∘⊣)÷○(×´1⊸+)↕∘⊣)˘ # Combination function (APL's dyadic !) - Ic ← {m‿n←𝕨 ⋄ ⊑-˝(m-↕m) +˝∘(C˘) n-(»1+𝕩)∾˘𝕩} + Ic ← { + 𝕊⁼: 𝕨Ci𝕩; + m‿n𝕊𝕩: + ⊑-˝(m-↕m) +˝∘(C˘) n-(»1+𝕩)∾˘𝕩 + } Ci ← { + 𝕊⁼: 𝕨Ic𝕩; 0‿n𝕊𝕩: ⟨⟩; - m‿n←𝕨 + m‿n𝕊𝕩: v←+`(m-1)C(1-m)↓⌽↕n k←(v>𝕩)⊐1 k∾(1+k)+(𝕨-1∾1+k)𝕊(𝕩-k⊏0∾v) @@ -133,6 +140,7 @@ IndexFromCombination‿CombinationFromIndex ← { } ! 11 ≡ 4‿6 IndexFromCombination 1‿2‿3‿5 ! 1‿2‿3‿5 ≡ 4‿6 CombinationFromIndex 11 +! 11 ≡ 4‿6 CombinationFromIndex⁼ 4‿6 CombinationFromIndex 11 # 24 SymmetricArray ← ⍉⊸≡ ∧ 1⊸⍉⊸≡ |