From 7ac9846329cc231c79fa1158f1e1f1d5fc96bc22 Mon Sep 17 00:00:00 2001
From: Mistivia <i@mistivia.com>
Date: Thu, 24 Apr 2025 17:16:21 +0800
Subject: permutational-primes

---
 4-kyu/permutational-primes.hs | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 4-kyu/permutational-primes.hs

diff --git a/4-kyu/permutational-primes.hs b/4-kyu/permutational-primes.hs
new file mode 100644
index 0000000..6aedafe
--- /dev/null
+++ b/4-kyu/permutational-primes.hs
@@ -0,0 +1,40 @@
+-- https://www.codewars.com/kata/55eec0ee00ae4a8fa0000075
+module PermutationalPrimes (permutationalPrimes) where
+
+import Control.Monad
+import qualified Data.List as L
+import qualified Data.Set as Set
+
+deduplicateList :: Ord a => [a] -> [a]
+deduplicateList = Set.toList . Set.fromList
+
+permutations :: Int -> Int -> [Int]
+permutations n upperLimit =
+  filter (<= upperLimit) $
+    map read $ filter (\lst -> head lst /= '0') $
+      lstPermutations $ show n
+
+lstPermutations = L.permutations
+
+primes = filterPrime [2..] where
+  filterPrime (p:xs) =
+    p : filterPrime [x | x <- xs, x `mod` p /= 0]
+
+
+permuatationsPrimeCnt primeSet n upperLimit =
+  if foldl1 min permPrimes == n then (length permPrimes - 1)
+  else 0  
+  where
+    permPrimes = deduplicateList $ filter isPrime $ permutations n upperLimit
+        where isPrime x = Set.member x primeSet
+
+permutationalPrimes :: Int -> Int -> Maybe (Int, Int, Int)
+permutationalPrimes nMax kPerms =
+    if ret /= [] then
+        Just (length ret, head ret, foldl1 max ret)
+    else 
+        Nothing
+    where
+        ret = seq primeSet $ filter (\n -> kPerms == permuatationsPrimeCnt primeSet n nMax) $
+                Set.toList primeSet
+              where primeSet = Set.fromList $ takeWhile (<=nMax) primes
-- 
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