# 1650. Lowest Common Ancestor of a Binary Tree III

Given two nodes of a binary tree `p` and `q`, return their lowest common ancestor (LCA).

Each node will have a reference to its parent node. The definition for `Node` is below:

`class Node {    public int val;    public Node left;    public Node right;    public Node parent;}`

According to the definition of LCA on Wikipedia: “The lowest common ancestor of two nodes p and q in a tree T is the lowest node that has both p and q as descendants (where we allow a node to be a descendant of itself).”

Example 1:

`Input: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 1Output: 3Explanation: The LCA of nodes 5 and 1 is 3.`

Example 2:

`Input: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 4Output: 5Explanation: The LCA of nodes 5 and 4 is 5 since a node can be a descendant of itself according to the LCA definition.`

Example 3:

`Input: root = [1,2], p = 1, q = 2Output: 1`

Constraints:

• The number of nodes in the tree is in the range `[2, 105]`.
• `-109 <= Node.val <= 109`
• All `Node.val` are unique.
• `p != q`
• `p` and `q` exist in the tree.