added assignment 6 ex 2

src/Assignment6/Ex2.sc

@@ -0,0 +1,38 @@
+
+def isPrime(i: Int): Boolean =
+    i match {
+        case i if i <= 1 => false
+        case 2 => true
+        case _ => !(2 to (i - 1)).exists(x => i % x == 0)
+    }
+
+def primeSum(max: Int): List[(Int, Int)] =
+    for {
+        i <- (1 to max).toList
+        j <- (1 to max).toList
+        if (isPrime(i + j))
+    } yield (i, j)
+
+
+def uniquePermutations(permutations: List[(Int, Int)]): List[(Int, Int)] = {
+  permutations match {
+    case Nil => Nil
+    case (a, b)::rest if rest contains(b, a) => uniquePermutations(rest)
+    case head::rest => head::uniquePermutations(rest)
+  }
+}
+
+def uniquePermutations2(permutations: List[(Int, Int)]): List[(Int, Int)] = {
+  permutations.foldRight(List.empty[(Int, Int)])(
+    (e, acc) => {
+      e match {
+        case (a, b) if acc contains (b, a) => acc
+        case _ => e::acc
+      }
+    }
+  )
+}
+
+val perms = primeSum(10)
+uniquePermutations(perms)
+uniquePermutations2(perms)