Find The Duplicate Number

Medium Linked List
Find the one duplicated number in an array of n+1 integers without modifying it.

Full statement, examples and constraints: see the original problem link below.

A full in-site walkthrough for this problem is coming soon.

View solution & discussion on the original problem ↗
Write your solution in the editor, then hit “Mark solved”. In-browser run & auto-check is coming soon.