Update 05_quicksort.kt (#267)

remove unnecessary line

04_quicksort/kotlin/05_quicksort.kt

@@ -3,10 +3,9 @@ fun quickSort(list: List<Int>): List<Int> {
     if (list.size <= 1) return list
     // recursive case
     val pivot = list[list.size / 2]
-    val equal = list.filter { it == pivot }
     val less = list.filter { it < pivot }
     val greater = list.filter { it > pivot }
-    return quickSort(less) + equal + quickSort(greater)
+    return quickSort(less) + pivot + quickSort(greater)
 }
 
 fun main(args: Array<String>) = println(quickSort(listOf(10, 5, 2, 3))) // [2, 3, 5, 10]