- Difficulty: Medium
- Tags: LeetCode, Medium, Tree, Depth-First Search, Hash Table, Binary Tree, leetcode-1676, O(n), O(h), 🔒, DFS, Stack
Problem
Given the root
of a binary tree and an array of TreeNode
objects nodes
, return the lowest common ancestor (LCA) of all the nodes in nodes
. All the nodes will exist in the tree, and all values of the tree's nodes are unique.
Extending the definition of LCA on Wikipedia: "The lowest common ancestor of n
nodes p1
, p2
, ..., pn
in a binary tree T
is the lowest node that has every pi
as a descendant (where we allow a node to be a descendant of itself) for every valid i
". A descendant of a node x
is a node y
that is on the path from node x
to some leaf node.
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Example 1:
Input: root = [3,5,1,6,2,0,8,null,null,7,4], nodes = [4,7] Output: 2 Explanation: The lowest common ancestor of nodes 4 and 7 is node 2.
Example 2:
Input: root = [3,5,1,6,2,0,8,null,null,7,4], nodes = [1] Output: 1 Explanation: The lowest common ancestor of a single node is the node itself.
Example 3:
Input: root = [3,5,1,6,2,0,8,null,null,7,4], nodes = [7,6,2,4] Output: 5 Explanation: The lowest common ancestor of the nodes 7, 6, 2, and 4 is node 5.
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Constraints:
- The number of nodes in the tree is in the range
[1, 104]
. -109 <= Node.val <= 109
- All
Node.val
are unique. - All
nodes[i]
will exist in the tree. - All
nodes[i]
are distinct.