re: Find the First Duplicate in a JavaScript Array VIEW POST


Follow up would be to do this in constant space where the complexity doesn’t exceed O(n*2). For that you can use the Floyd’s Turtoise and Hare algorithm.


Thanks for the suggestion! I'm trying to learn more about space/time complexity as I go along, so I really appreciate the nod for a direction to look in.


Sorry, I just don't see how that algorithm helps us in this case. I've only used that to solve problems with cycles, and couldn't find any information as to how the Tortoise and Hare algorithm helps us solve this problem.

If you could post your source or a sample solution, I would appreciate it.


You’re right, i misread the question. I recently had this question during my FAANG phone interview, i eventually ended up using binary search. Then he went on about turtle and hare, bla bla. Luckily he deemed it not really important to know, but a other interviewer might not be that nice.

This was the question btw: leetcode.com/problems/find-the-dup...

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