0608. Tree Node

https://leetcode.com/problems/tree-node

Description

Given a table tree, id is identifier of the tree node and p_id is its parent node's id.

+----+------+
| id | p\_id |
+----+------+
| 1  | null |
| 2  | 1    |
| 3  | 1    |
| 4  | 2    |
| 5  | 2    |
+----+------+

Each node in the tree can be one of three types:

• Leaf: if the node is a leaf node.

• Root: if the node is the root of the tree.

• Inner: If the node is neither a leaf node nor a root node.

Write a query to print the node id and the type of the node. Sort your output by the node id. The result for the above sample is:

+----+------+
| id | Type |
+----+------+
| 1  | Root |
| 2  | Inner|
| 3  | Leaf |
| 4  | Leaf |
| 5  | Leaf |
+----+------+

Explanation

• Node '1' is root node, because its parent node is NULL and it has child node '2' and '3'.

• Node '2' is inner node, because it has parent node '1' and child node '4' and '5'.

• Node '3', '4' and '5' is Leaf node, because they have parent node and they don't have child node.

• And here is the image of the sample tree as below:

			  1
			/   \
                      2       3
                    /   \
                  4       5

Note

If there is only one node on the tree, you only need to output its root attributes.

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