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_iii_compact.go

@@ -0,0 +1,27 @@
+// File: preorder_traversal_i_compact.go
+// Created Time: 2023-05-09
+// Author: Reanon (793584285@qq.com)
+
+package chapter_backtracking
+
+import (
+	. "github.com/krahets/hello-algo/pkg"
+)
+
+/* 前序遍历：例题三 */
+func preOrderIII(root *TreeNode, res *[][]*TreeNode, path *[]*TreeNode) {
+	// 剪枝
+	if root == nil || root.Val == 3 {
+		return
+	}
+	// 尝试
+	*path = append(*path, root)
+	if int(root.Val) == 7 {
+		// 记录解
+		*res = append(*res, *path)
+	}
+	preOrderIII(root.Left, res, path)
+	preOrderIII(root.Right, res, path)
+	// 回退
+	*path = (*path)[:len(*path)-1]
+}