ALGODAILY

September 19, 2020

“Information is useless if it is not applied to something important or if you will forget it before you have a chance to apply it.”

- Tim Ferriss

Day 9: Lowest Common Ancestor

You're given a binary search tree and two of its child nodes as parameters. Can you write a method lowestCommonAncestor(root: Node, node1: Node, node2: Node) to identify the lowest common ancestor of the two nodes? The lowest common ancestor is the deepest node that has both of the two nodes as descendants.

In the below example, the lowest common ancestor of node 5 and 8 is 7.

/*
       7
      / \
     4   8
    / \
   1   5
*/

The method will called in the following manner: lowestCommonAncestor(root, node1, node2);.

You can assume our standard node definition for the tree vertices:

function Node(val) {
  this.val = val;
  this.left = this.right = null;
}

Click to solve →

As always, you can see the solution and a full step by step explanation at this link.

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