Solving Lowest Common Ancestor of a Binary Tree in Javascript. Please try yourself first to solve the problem and submit your implementation to LeetCode before looking into solution.

Problem Description

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.

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).”

Given the following binary tree: root = [3,5,1,6,2,0,8,null,null,7,4]

        _______3______
	       /              \
	    ___5__          ___1__
	   /      \        /      \
	   6      _2       0       8
	         /  \
	         7   4

Examples

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

Note

  • All of the nodes' values will be unique.
  • p and q are different and both values will exist in the binary tree.

See the full details of the problem Lowest Common Ancestor of a Binary Tree at LeetCode

Originally posted at: @github.com/ignacio-chiazzo/Algorithms-Leetcode-Javascript