Added ShakerSort with tests

src/main/kotlin/sort/ShakerSort.kt

@@ -0,0 +1,49 @@
+package sort
+
+/**
+ * This function implements the Shaker Sort.
+ *
+ * @param array The array to be sorted
+ * Sorts the array in increasing order
+ *
+ * Worst-case performance       O(n2)
+ * Best-case performance        O(n)
+ * Average-case performance     O(n2)
+ * Worst-case space complexity  O(n2)
+ */
+fun <T : Comparable<T>> shakerSort(arr: Array<T>) {
+    var left = 0
+    var right = arr.lastIndex
+    var swapped: Boolean
+
+    do {
+        swapped = false
+
+        for (i in left until right) {
+            if (arr[i] > arr[i + 1]) {
+                val temp = arr[i]
+                arr[i] = arr[i + 1]
+                arr[i + 1] = temp
+                swapped = true
+            }
+        }
+
+        if (!swapped) {
+            break
+        }
+
+        swapped = false
+        right--
+
+        for (i in right downTo left) {
+            if (arr[i] > arr[i + 1]) {
+                val temp = arr[i]
+                arr[i] = arr[i + 1]
+                arr[i + 1] = temp
+                swapped = true
+            }
+        }
+
+        left++
+    } while (swapped)
+}

src/test/kotlin/sort/ShakerSortTest.kt

@@ -0,0 +1,28 @@
+package sort
+
+import org.junit.Assert.assertArrayEquals
+import org.junit.Test
+
+class ShakerSortTest {
+
+    @Test
+    fun testShakeSort() {
+        val array = arrayOf(4,3,2,8,1)
+        shakerSort(array)
+        assertArrayEquals(array, arrayOf(1,2,3,4,8))
+    }
+
+    @Test
+    fun testShakeSort2() {
+        val array = arrayOf(20, 5, 16, -1, 6)
+        shakerSort(array)
+        assertArrayEquals(array, arrayOf(-1, 5, 6, 16, 20))
+    }
+
+    @Test
+    fun testShakeSort3() {
+        val array = arrayOf("A", "D", "E", "C", "B")
+        shakerSort(array)
+        assertArrayEquals(array, arrayOf("A", "B", "C", "D", "E"))
+    }
+}