Adding merge sort in scala

sort/merge_sort/scala/MergeSort.scala

@@ -0,0 +1,44 @@
+object MergeSort {
+
+  def merge(leftArr: Array[Int], rightArr: Array[Int]) = {
+    var leftIndex = 0
+    var rightIndex = 0
+
+    var sortedArr = Array.empty[Int]
+
+    while (leftIndex < leftArr.length && rightIndex < rightArr.length) {
+      if (leftArr(leftIndex) < rightArr(rightIndex)) {
+        sortedArr = sortedArr.appended(leftArr(leftIndex))
+        leftIndex += 1
+      } else {
+        sortedArr = sortedArr.appended(rightArr(rightIndex))
+        rightIndex += 1
+      }
+    }
+
+    val restLeft = leftArr.slice(leftIndex, leftArr.length)
+    val restRight = rightArr.slice(rightIndex, rightArr.length)
+
+    sortedArr ++ restLeft ++ restRight
+  }
+
+  def mergeSort(arr: Array[Int]): Array[Int] = {
+      if (arr.length <= 1) return arr
+
+      val mid = arr.length / 2
+      var (left, right) = arr.splitAt(mid)
+
+      left = mergeSort(left)
+      right = mergeSort(right)
+
+      merge(left, right)
+  }
+
+
+  def main(args: Array[String]): Unit = {
+    val arr = Array(11, 3, 1, 13, 4, 5, 12, 9, 2, 6, 8, 7, 10)
+    val sortedArray = mergeSort(arr)
+    println(sortedArray.mkString(", "))
+  }
+
+}