feat(go/backtracking): add go code (#488)

* feat(go/backtracking): add go code

* feat(backtracking): add n_queens in go

* feat(backtracking): add /preorder_traversal_i_compact in go

* feat(backtracking): add /preorder_traversal_ii_compact in go

* feat(backtracking): add /preorder_traversal_ii_template in go

* feat(backtracking): add preorder_traversal_iii_compact in go

* feat(backtracking): add preorder_traversal_test in go

* feat(backtracking): add permutations_i in go

* feat(backtracking): add permutations_ii in go

* feat(backtracking): add permutation_test in go

* feat(backtracking): fix bug in go

* Update permutations_i.go

---------

Co-authored-by: Yudong Jin <krahets@163.com>

codes/go/chapter_backtracking/preorder_traversal_test.go

@@ -0,0 +1,91 @@
+// File: preorder_traversal_i_compact_test.go
+// Created Time: 2023-05-09
+// Author: Reanon (793584285@qq.com)
+
+package chapter_backtracking
+
+import (
+	"fmt"
+	"testing"
+
+	. "github.com/krahets/hello-algo/pkg"
+)
+
+func TestPreorderTraversalICompact(t *testing.T) {
+	/* 初始化二叉树 */
+	root := ArrToTree([]any{1, 7, 3, 4, 5, 6, 7})
+	fmt.Println("\n初始化二叉树")
+	PrintTree(root)
+
+	// 前序遍历
+	res := make([]*TreeNode, 0)
+	preOrderI(root, &res)
+
+	fmt.Println("\n输出所有值为 7 的节点")
+	for _, node := range res {
+		fmt.Printf("%v ", node.Val)
+	}
+	fmt.Println()
+}
+
+func TestPreorderTraversalIICompact(t *testing.T) {
+	/* 初始化二叉树 */
+	root := ArrToTree([]any{1, 7, 3, 4, 5, 6, 7})
+	fmt.Println("\n初始化二叉树")
+	PrintTree(root)
+
+	// 前序遍历
+	path := make([]*TreeNode, 0)
+	res := make([][]*TreeNode, 0)
+	preOrderII(root, &res, &path)
+
+	fmt.Println("\n输出所有根节点到节点 7 的路径")
+	for _, path := range res {
+		for _, node := range path {
+			fmt.Printf("%v ", node.Val)
+		}
+		fmt.Println()
+	}
+}
+
+func TestPreorderTraversalIIICompact(t *testing.T) {
+	/* 初始化二叉树 */
+	root := ArrToTree([]any{1, 7, 3, 4, 5, 6, 7})
+	fmt.Println("\n初始化二叉树")
+	PrintTree(root)
+
+	// 前序遍历
+	path := make([]*TreeNode, 0)
+	res := make([][]*TreeNode, 0)
+	preOrderIII(root, &res, &path)
+
+	fmt.Println("\n输出所有根节点到节点 7 的路径，且路径中不包含值为 3 的节点")
+	for _, path := range res {
+		for _, node := range path {
+			fmt.Printf("%v ", node.Val)
+		}
+		fmt.Println()
+	}
+}
+
+func TestPreorderTraversalIIITemplate(t *testing.T) {
+	/* 初始化二叉树 */
+	root := ArrToTree([]any{1, 7, 3, 4, 5, 6, 7})
+	fmt.Println("\n初始化二叉树")
+	PrintTree(root)
+
+	// 回溯算法
+	res := make([][]*TreeNode, 0)
+	state := make([]*TreeNode, 0)
+	choices := make([]*TreeNode, 0)
+	choices = append(choices, root)
+	backtrackIII(&state, &choices, &res)
+
+	fmt.Println("\n输出所有根节点到节点 7 的路径，且路径中不包含值为 3 的节点")
+	for _, path := range res {
+		for _, node := range path {
+			fmt.Printf("%v ", node.Val)
+		}
+		fmt.Println()
+	}
+}