Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.
According to the definition of LCA on Wikipedia: βThe lowest common ancestor is defined between two nodes p
and q
as the lowest node in T
that has both p
and q
as descendants (where we allow a node to be a descendant of itself).β
Example 1:
6
/ \
2 8
/ \ / \
0 4 7 9
/ \
3 5
Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8
Output: 6
Explanation: The LCA of nodes 2 and 8 is 6.
Example 2:
6
/ \
2 8
/ \ / \
0 4 7 9
/ \
3 5
Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4
Output: 2
Explanation: The LCA of nodes 2 and 4 is 2, since a node can be a descendant of
itself according to the LCA definition.
Example 3:
Input: root = [2,1], p = 2, q = 1
Output: 2
Constraints:
 The number of nodes in the tree is in the range
[2, 10^{5}]
. 10^{9} <= Node.val <= 10^{9}
 All
Node.val
are unique. p != q
p
andq
will exist in the BST.

