September 2017 Update

Task/Sorting-algorithms-Heapsort/Kotlin/sorting-algorithms-heapsort.kotlin

@@ -0,0 +1,48 @@
+// version 1.1.0
+
+fun heapSort(a: IntArray) {
+    heapify(a)
+    var end = a.size - 1
+    while (end > 0) {
+        val temp = a[end]
+        a[end] = a[0]
+        a[0] = temp
+        end--
+        siftDown(a, 0, end)
+    }
+}
+
+fun heapify(a: IntArray) {
+    var start = (a.size - 2) / 2
+    while (start >= 0) {
+        siftDown(a, start, a.size - 1)
+        start--
+    }
+}
+
+fun siftDown(a: IntArray, start: Int, end: Int) {
+    var root = start
+    while (root * 2 + 1 <= end) {
+        var child = root * 2 + 1
+        if (child + 1 <= end && a[child] < a[child + 1]) child++
+        if (a[root] < a[child]) {
+            val temp = a[root]
+            a[root] = a[child]
+            a[child] = temp
+            root = child
+        }
+        else return
+    }
+}
+
+fun main(args: Array<String>) {
+    val aa = arrayOf(
+        intArrayOf(100, 2, 56, 200, -52, 3, 99, 33, 177, -199),
+        intArrayOf(4, 65, 2, -31, 0, 99, 2, 83, 782, 1),
+        intArrayOf(12, 11, 15, 10, 9, 1, 2, 3, 13, 14, 4, 5, 6, 7, 8)
+    )
+    for (a in aa) {
+        heapSort(a)
+        println(a.joinToString(", "))
+    }
+}