Add Go codes to docs, including

the chapter of stack and queue, the chapter of tree.

codes/go/pkg/print_utils.go

@@ -0,0 +1,98 @@
+// File: print_utils.go
+// Created Time: 2022-12-03
+// Author: Reanon (793584285@qq.com), Krahets (krahets@163.com)
+
+package pkg
+
+import (
+	"container/list"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+func PrintSlice(nums []int) {
+	fmt.Printf("%v", nums)
+	fmt.Println()
+}
+
+// PrintList Print a list
+func PrintList(list *list.List) {
+	e := list.Front()
+	// 强转为 string, 会影响效率
+	fmt.Print("[")
+	for e.Next() != nil {
+		fmt.Print(e.Value, " ")
+		e = e.Next()
+	}
+	fmt.Print(e.Value, "]\n")
+}
+
+// PrintLinkedList Print a linked list
+func PrintLinkedList(node *ListNode) {
+	if node == nil {
+		return
+	}
+	var builder strings.Builder
+	for node.Next != nil {
+		builder.WriteString(strconv.Itoa(node.Val) + " -> ")
+		node = node.Next
+	}
+	builder.WriteString(strconv.Itoa(node.Val))
+	fmt.Println(builder.String())
+}
+
+// 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)
+}