Lowest Common Ancestor in a Binary Tree

In binary trees, for given two nodes a and b, the lowest common ancestor is the node of which both a and b are descendants. Here a node can be descendant of itself.

In the above image, if we consider two nodes 2 and 3 then their lowest common ancestor will be node 1.
Similarly, the lowest common ancestor of 4 and 5 will be 2 and that of 3 and 4 would be 1.
The lowest common ancestor is the common and shared descendant of both given nodes.
LCA is used in many other binary tree problems like in d...