fix binary_search_tree code

codes/go/chapter_tree/binary_search_tree_test.go

@@ -10,8 +10,12 @@ import (
 )
 
 func TestBinarySearchTree(t *testing.T) {
-	nums := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
-	bst := newBinarySearchTree(nums)
+	bst := newBinarySearchTree()
+	nums := []int{8, 4, 12, 2, 6, 10, 14, 1, 3, 5, 7, 9, 11, 13, 15}
+	// 请注意，不同的插入顺序会生成不同的二叉树，该序列可以生成一个完美二叉树
+	for _, num := range nums {
+		bst.insert(num)
+	}
 	fmt.Println("\n初始化的二叉树为:")
 	bst.print()