Finding the common ancestor in a binary tree

Question

This question was asked to me in an interview: I have a binary tree and I have to find the common ancestor (parent) given two random nodes of that tree. I am also given a point

Answer 1

1. Pre order traversal unless any 1 of the node is met and save the nodes visited uptil now.

2. Inorder traversal,start saving the nodes when any 1 (of the two provided nodes) node is met,and save the list until the next node is met.

3. post order traversal,start saving the nodes when both the nodes hav been visited...

               A         

      B                  C         

  D       E          F       G       

H   I   J   K      L   M   N   O     

Suppose H and E are two random nodes.

1. ABDH
2. HDIBJE
3. EBLMENOGCA

Find the first node common in all three...