Merge pull request #133 from Zentreax/main

Added Heap Sort in Golang.

Golang/sorting/heap_sort.go

@@ -0,0 +1,83 @@
+package main
+
+import "fmt"
+
+type minheap struct {
+	arr []int
+}
+
+func newMinHeap(arr []int) *minheap {
+	minheap := &minheap{
+		arr: arr,
+	}
+	return minheap
+}
+
+func (m *minheap) leftchildIndex(index int) int {
+	return 2*index + 1
+}
+
+func (m *minheap) rightchildIndex(index int) int {
+	return 2*index + 2
+}
+
+func (m *minheap) swap(first, second int) {
+	temp := m.arr[first]
+	m.arr[first] = m.arr[second]
+	m.arr[second] = temp
+}
+
+func (m *minheap) leaf(index int, size int) bool {
+	if index >= (size/2) && index <= size {
+		return true
+	}
+	return false
+}
+
+func (m *minheap) downHeapify(current int, size int) {
+	if m.leaf(current, size) {
+		return
+	}
+	smallest := current
+	leftChildIndex := m.leftchildIndex(current)
+	rightRightIndex := m.rightchildIndex(current)
+	if leftChildIndex < size && m.arr[leftChildIndex] < m.arr[smallest] {
+		smallest = leftChildIndex
+	}
+	if rightRightIndex < size && m.arr[rightRightIndex] < m.arr[smallest] {
+		smallest = rightRightIndex
+	}
+	if smallest != current {
+		m.swap(current, smallest)
+		m.downHeapify(smallest, size)
+	}
+	return
+}
+
+func (m *minheap) buildMinHeap(size int) {
+	for index := ((size / 2) - 1); index >= 0; index-- {
+		m.downHeapify(index, size)
+	}
+}
+
+func (m *minheap) sort(size int) {
+	m.buildMinHeap(size)
+	for i := size - 1; i > 0; i-- {
+		m.swap(0, i)
+		m.downHeapify(0, i)
+	}
+}
+
+func (m *minheap) print() {
+	for _, val := range m.arr {
+		fmt.Println(val)
+	}
+}
+
+func main() {
+	inputArray := []int{6, 5, 3, 7, 2, 8, -1}
+	minHeap := newMinHeap(inputArray)
+	minHeap.sort(len(inputArray))
+	minHeap.print()
+	fmt.Scanln()
+}