Scala : generalize merge sort

1 files changed, 7 insertions, 5 deletions

diff --git a/Scala/sandbox/10-merge-sort.scala b/Scala/sandbox/10-merge-sort.scala
index 92296e2..5cf0b44 100644
--- a/Scala/sandbox/10-merge-sort.scala
+++ b/Scala/sandbox/10-merge-sort.scala
@@ -1,25 +1,27 @@
 object MergeSort
 {
 
-  def msort(xs: List[Int]): List[Int] = {
+  def msort[T](xs: List[T])(lt: (T, T) => Boolean): List[T] = {
     val n = xs.length/2
     if (n==0) xs
     else {
-      def merge(xs: List[Int], ys: List[Int]): List[Int] = (xs, ys) match {
+      def merge(xs: List[T], ys: List[T]): List[T] = (xs, ys) match {
         case (Nil, ys) => ys
         case (xs, Nil) => xs
         case (x :: xs1, y :: ys1) => {
-          if (x < y) x :: merge(xs1, ys)
+          if (lt(x, y)) x :: merge(xs1, ys)
           else y :: merge(xs, ys1)
         }
       }
       val (fst, snd) = xs splitAt n
-      merge(msort(fst), msort(snd))
+      merge(msort(fst)(lt), msort(snd)(lt))
     }
   }
 
   def run = {
     println("MergeSort")
-    println(msort(List(2, 8, -2, 9, 2, 6, 0, 7, 1)))
+    val nums = List(2, 8, -2, 9, 2, 6, 0, 7, 1)
+    val sorted = msort(nums)((x: Int, y: Int) => x < y)
+    println(sorted)
   }
 }