Data commit

Task/Find-the-missing-permutation/Scala/find-the-missing-permutation-1.scala

@@ -0,0 +1,40 @@
+def fat(n: Int) = (2 to n).foldLeft(1)(_*_)
+def perm[A](x: Int, a: Seq[A]): Seq[A] = if (x == 0) a else {
+  val n = a.size
+  val fatN1 = fat(n - 1)
+  val fatN = fatN1 * n
+  val p = x / fatN1 % fatN
+  val (before, Seq(el, after @ _*)) = a splitAt p
+  el +: perm(x % fatN1, before ++ after)
+}
+def findMissingPerm(start: String, perms: Array[String]): String = {
+  for {
+    i <- 0 until fat(start.size)
+    p = perm(i, start).mkString
+  } if (!perms.contains(p)) return p
+  ""
+}
+val perms = """ABCD
+CABD
+ACDB
+DACB
+BCDA
+ACBD
+ADCB
+CDAB
+DABC
+BCAD
+CADB
+CDBA
+CBAD
+ABDC
+ADBC
+BDCA
+DCBA
+BACD
+BADC
+BDAC
+CBDA
+DBCA
+DCAB""".stripMargin.split("\n")
+println(findMissingPerm(perms(0), perms))

Task/Find-the-missing-permutation/Scala/find-the-missing-permutation-2.scala

@@ -0,0 +1,2 @@
+println("missing perms: "+("ABCD".permutations.toSet
+  --"ABCD CABD ACDB DACB BCDA ACBD ADCB CDAB DABC BCAD CADB CDBA CBAD ABDC ADBC BDCA DCBA BACD BADC BDAC CBDA DBCA DCAB".stripMargin.split(" ").toSet))