2016 Update

Task/Sorting-algorithms-Merge-sort/Kotlin/sorting-algorithms-merge-sort.kotlin

@@ -0,0 +1,50 @@
+fun mergeSort(list: List<Int>): List<Int> {
+    if (list.size <= 1) {
+        return list
+    }
+
+    val left = mutableListOf<Int>()
+    val right = mutableListOf<Int>()
+
+    val middle = list.size / 2
+    list.forEachIndexed { index, number ->
+        if (index < middle) {
+            left.add(number)
+        } else {
+            right.add(number)
+        }
+    }
+
+    fun merge(left: List<Int>, right: List<Int>): List<Int> = mutableListOf<Int>().apply {
+        var indexLeft = 0
+        var indexRight = 0
+
+        while (indexLeft < left.size && indexRight < right.size) {
+            if (left[indexLeft] <= right[indexRight]) {
+                add(left[indexLeft])
+                indexLeft++
+            } else {
+                add(right[indexRight])
+                indexRight++
+            }
+        }
+
+        while (indexLeft < left.size) {
+            add(left[indexLeft])
+            indexLeft++
+        }
+
+        while (indexRight < right.size) {
+            add(right[indexRight])
+            indexRight++
+        }
+    }
+
+    return merge(mergeSort(left), mergeSort(right))
+}
+
+fun main(args: Array<String>) {
+    val numbers = listOf(5, 2, 3, 17, 12, 1, 8, 3, 4, 9, 7)
+    println("Unsorted: $numbers")
+    println("Sorted: ${mergeSort(numbers)}")
+}