code kata 20230805

binary_tree_230804/main_test.go

@@ -0,0 +1,169 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+)
+
+type node struct {
+	left  *node
+	right *node
+	value string
+}
+
+func preOrder(n *node) {
+	if n != nil {
+		visit(n)
+		preOrder(n.left)
+		preOrder(n.right)
+	}
+}
+
+func preOrder2(n *node) {
+	stack := NewStack()
+	p := n
+	for p != nil || !stack.IsEmpty() {
+		if p != nil {
+			stack.Push(p)
+			visit(p)
+			p = p.left
+		} else {
+			x, err := stack.Pop()
+			if err != nil {
+				fmt.Print(err.Error())
+				p = nil
+				break
+			}
+			p = x.(*node)
+			p = p.right
+		}
+	}
+}
+
+func inOrder(n *node) {
+	if n != nil {
+		inOrder(n.left)
+		visit(n)
+		inOrder(n.right)
+	}
+}
+
+func inOrder2(n *node) {
+	stack := NewStack()
+	p := n
+	for p != nil || !stack.IsEmpty() {
+		if p != nil {
+			stack.Push(p)
+			p = p.left
+		} else {
+			x, err := stack.Pop()
+			if err != nil {
+				fmt.Print(err.Error())
+				p = nil
+				break
+			}
+			p = x.(*node)
+			visit(p)
+			p = p.right
+		}
+	}
+}
+
+func postOrder(n *node) {
+	if n != nil {
+		postOrder(n.left)
+		postOrder(n.right)
+		visit(n)
+	}
+}
+
+func postOrder2(n *node) {
+	stack := NewStack()
+	p := n
+	var r *node = nil
+	for p != nil || !stack.IsEmpty() {
+		if p != nil {
+			stack.Push(p)
+			p = p.left
+		} else {
+			x := stack.Top()
+			if x == nil {
+				break
+			}
+			p = x.(*node)
+			if p.right != nil && p.right != r {
+				p = p.right
+				stack.Push(p)
+				p = p.left
+			} else {
+				x, err := stack.Pop()
+				if err != nil {
+					fmt.Print(err.Error())
+					p = nil
+					break
+				}
+				p = x.(*node)
+				visit(p)
+				r = p
+				p = nil
+			}
+		}
+	}
+}
+
+func visit(n *node) {
+	fmt.Printf("Visiting Node: %s\n", n.value)
+}
+
+func makeBinaryTree() *node {
+	ln1 := &node{
+		value: "D",
+	}
+	ln2 := &node{
+		value: "E",
+	}
+	ln := &node{
+		value: "B",
+		left:  ln1,
+		right: ln2,
+	}
+	rn := &node{
+		value: "C",
+	}
+	n := &node{
+		value: "A",
+		left:  ln,
+		right: rn,
+	}
+	return n
+}
+
+func TestPreOrder(t *testing.T) {
+	n := makeBinaryTree()
+	preOrder(n)
+}
+
+func TestPreOrder2(t *testing.T) {
+	n := makeBinaryTree()
+	preOrder2(n)
+}
+
+func TestInOrder(t *testing.T) {
+	n := makeBinaryTree()
+	inOrder(n)
+}
+
+func TestInOrder2(t *testing.T) {
+	n := makeBinaryTree()
+	inOrder2(n)
+}
+
+func TestPostOrder(t *testing.T) {
+	n := makeBinaryTree()
+	postOrder(n)
+}
+
+func TestPostOrder2(t *testing.T) {
+	n := makeBinaryTree()
+	postOrder2(n)
+}

binary_tree_230804/stack.go

@@ -0,0 +1,39 @@
+package main
+
+import "errors"
+
+type Stack []interface {
+}
+
+func NewStack() Stack {
+	return Stack{}
+}
+
+func (s Stack) IsEmpty() bool {
+	return len(s) == 0
+}
+
+func (s *Stack) Push(item interface{}) error {
+	*s = append(*s, item)
+	return nil
+}
+
+func (s *Stack) Pop() (interface{}, error) {
+	if s.IsEmpty() {
+		return nil, errors.New("stack is empty")
+	}
+	ret := (*s)[len(*s)-1]
+	*s = (*s)[:len(*s)-1]
+	return ret, nil
+}
+
+func (s Stack) Top() interface{} {
+	if s.IsEmpty() {
+		return nil
+	}
+	return s[len(s)-1]
+}
+
+func (s Stack) Len() int {
+	return len(s)
+}