Longest Common ancestor in tree in O(n) time

[sam20code]

This issue is about [Algo/DS Name](link to resource for the Algo/DS).

• [ ] Issue Title is in form Algo/DS Name [Language].
• [ ] I searched or browsed the repo’s other issues to ensure this is not a duplicate.
• [ ] This Algo/DS is worth adding to this repository.
• [ ] Assign this issue to me (I want to work on this).
  • [ ] I ensure that I am not already assigned to 2 or more issues.
• [ ] I will send my PR only after I'm assigned to this issue by any maintainer.
• [ ] I understand that I will be unassigned from this issue if I fail to send a PR for this within a week.

[sam20code]

@iiitv/project-maintainers I want to work on this issue

[theyashshahs]

@sam20code fill the issue body details :)

[theyashshahs]

ping @sam20code