Package g1101_1200.s1123_lowest_common_ancestor_of_deepest_leaves

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    1123 - Lowest Common Ancestor of Deepest Leaves.

    Medium

    Given the root of a binary tree, return the lowest common ancestor of its deepest leaves.

    Recall that:

    • The node of a binary tree is a leaf if and only if it has no children

    • The depth of the root of the tree is 0. if the depth of a node is d, the depth of each of its children is d + 1.

    • The lowest common ancestor of a set S of nodes, is the node A with the largest depth such that every node in S is in the subtree with root A.

    Example 1:

    Input: root = 3,5,1,6,2,0,8,null,null,7,4

    Output: 2,7,4

    Explanation: We return the node with value 2, colored in yellow in the diagram. The nodes coloured in blue are the deepest leaf-nodes of the tree. Note that nodes 6, 0, and 8 are also leaf nodes, but the depth of them is 2, but the depth of nodes 7 and 4 is 3.

    Example 2:

    Input: root = 1

    Output: 1

    Explanation: The root is the deepest node in the tree, and it's the lca of itself.

    Example 3:

    Input: root = 0,1,3,null,2

    Output: 2

    Explanation: The deepest leaf node in the tree is 2, the lca of one node is itself.

    Constraints:

    • The number of nodes in the tree will be in the range [1, 1000].

    • 0 <= Node.val <= 1000

    • The values of the nodes in the tree are unique.

    Note: This question is the same as 865: https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final TreeNode lcaDeepestLeaves(TreeNode root)
      final Integer getDep(TreeNode root)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait