feat(go): support basic pkg

codes/go/pkg/tree_node.go

@@ -0,0 +1,127 @@
+// File: tree_node.go
+// Created Time: 2022-11-25
+// Author: Reanon (793584285@qq.com)
+
+package pkg
+
+import (
+	"container/list"
+	"fmt"
+)
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func NewTreeNode(v int) *TreeNode {
+	return &TreeNode{
+		Left:  nil,
+		Right: nil,
+		Val:   v,
+	}
+}
+
+// ArrayToTree Generate a binary tree with an array
+func ArrayToTree(arr []int) *TreeNode {
+	if len(arr) <= 0 {
+		return nil
+	}
+	root := NewTreeNode(arr[0])
+	// Let container.list as queue
+	queue := list.New()
+	queue.PushBack(root)
+	i := 1
+	for queue.Len() > 0 {
+		// poll
+		node := queue.Remove(queue.Front()).(*TreeNode)
+		if i < len(arr) {
+			node.Left = NewTreeNode(arr[i])
+			queue.PushBack(node.Left)
+			i++
+		}
+		if i < len(arr) {
+			node.Right = NewTreeNode(arr[i])
+			queue.PushBack(node.Right)
+			i++
+		}
+	}
+	return root
+}
+
+// TreeToArray Serialize a binary tree to a list
+func TreeToArray(root *TreeNode) []int {
+	if root == nil {
+		return []int{}
+	}
+	arr := make([]int, 16)
+	queue := list.New()
+	queue.PushBack(root)
+	for queue.Len() > 0 {
+		node := queue.Remove(queue.Front()).(*TreeNode)
+		if node != nil {
+			arr = append(arr, node.Val)
+			queue.PushBack(node.Left)
+			queue.PushBack(node.Right)
+		} else {
+			arr = append(arr, -1)
+		}
+	}
+	return arr
+}
+
+// PrintTree Print a binary tree
+func PrintTree(root *TreeNode) {
+	PrintTreeHelper(root, nil, false)
+}
+
+// PrintTreeHelper Help to print a binary tree, hide more details
+// This tree printer is borrowed from TECHIE DELIGHT
+// https://www.techiedelight.com/c-program-print-binary-tree/
+func PrintTreeHelper(root *TreeNode, prev *trunk, isLeft bool) {
+	if root == nil {
+		return
+	}
+	prevStr := "    "
+	trunk := newTrunk(prev, prevStr)
+	PrintTreeHelper(root.Right, trunk, true)
+	if prev == nil {
+		trunk.str = "———"
+	} else if isLeft {
+		trunk.str = "/———"
+		prevStr = "   |"
+	} else {
+		trunk.str = "\\———"
+		prev.str = prevStr
+	}
+	showTrunk(trunk)
+	fmt.Println(root.Val)
+	if prev != nil {
+		prev.str = prevStr
+	}
+	trunk.str = "   |"
+	PrintTreeHelper(root.Left, trunk, false)
+}
+
+// trunk Help to Print tree structure
+type trunk struct {
+	prev *trunk
+	str  string
+}
+
+func newTrunk(prev *trunk, str string) *trunk {
+	return &trunk{
+		prev: prev,
+		str:  str,
+	}
+}
+
+func showTrunk(t *trunk) {
+	if t == nil {
+		return
+	}
+
+	showTrunk(t.prev)
+	fmt.Print(t.str)
+}