add heapsort in golang

Author: TonPC64

Sorting/HeapSort/go/HeapSort.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	a := []int{5, 109, 87, 4, 50, 908, 65, 22, 1, 36}
+	a = heapsort(a)
+	fmt.Println(a)
+}
+
+func heapsort(a []int) []int {
+	heapify(a, len(a))
+	end := len(a) - 1
+	for end > 0 {
+		a[end], a[0] = a[0], a[end]
+		end--
+		traverse(a, 0, end)
+	}
+	return a
+}
+
+func heapify(a []int, count int) {
+	start := int((count - 2) / 2)
+	for start >= 0 {
+		traverse(a, start, count-1)
+		start--
+	}
+
+}
+
+func traverse(a []int, start, end int) {
+	root := start
+	for (root*2 + 1) <= end {
+		child := root*2 + 1
+		swap := root
+		if a[swap] < a[child] {
+			swap = child
+		}
+		if (child+1) <= end && a[swap] < a[child+1] {
+			swap = child + 1
+		}
+		if swap != root {
+			a[root], a[swap] = a[swap], a[root]
+			root = swap
+		} else {
+			return
+		}
+	}
+}