Description
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: “The 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).”
Example 1:
![](https://github.com/goldennovember/leetcode-go/raw/93f1c4354769/figures/binarysearchtree_improved.png)
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:
![](https://github.com/goldennovember/leetcode-go/raw/93f1c4354769/figures/binarysearchtree_improved.png)
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
and q
will exist in the BST.