ThinkPHP中：使用递归写node_merge()函数

需求描述：

现有一个节点集合

可以视为一个二维数组

 1 array(5) {
 2   [0] => array(4) {
 3     ["id"] => string(1) "1"
 4     ["name"] => string(5) "Admin"
 5     ["title"] => string(12) "后台应用"
 6     ["pid"] => string(1) "0"
 7   }
 8   [1] => array(4) {
 9     ["id"] => string(1) "2"
10     ["name"] => string(5) "Index"
11     ["title"] => string(12) "前端应用"
12     ["pid"] => string(1) "0"
13   }
14   [2] => array(4) {
15     ["id"] => string(1) "3"
16     ["name"] => string(5) "Index"
17     ["title"] => string(12) "后台首页"
18     ["pid"] => string(1) "1"
19   }
20   [3] => array(4) {
21     ["id"] => string(1) "4"
22     ["name"] => string(10) "MsgManager"
23     ["title"] => string(12) "帖子管理"
24     ["pid"] => string(1) "1"
25   }
26   [4] => array(4) {
27     ["id"] => string(1) "5"
28     ["name"] => string(4) "Rbac"
29     ["title"] => string(10) "RBAC权限"
30     ["pid"] => string(1) "1"
31   }
32 }

数组arr01