Easy Linked List Question 38 of 224

How do you detect a cycle in a linked list?

DSA interview set · Speak this in 60–90 seconds · Faridabad & Delhi NCR

Key"user_id"

Hashslot 17

Valuethe record

Floyd's tortoise and hare: slow walks one, fast walks two

Why interviewers care about Linked List:

This is a process

question about Linked List.

Panels listen for order,

trade-offs, and what you would actually do on a DSA project - not buzzwords.

Stay structured

Name the idea, why it exists, then one short example.

Close cleanly

End with when you use it and one common pitfall.

Before you speak the answer, walk the interviewer through these steps:

1
Floyd's tortoise and hare:
slow walks one, fast walks two
2
they meet if a
cycle exists.
3
Time is O(n) and
space is O(1).
4
A hash set of
seen nodes is O(n) space and easier to explain if you have not practiced the meeting proof.
5
Common mistake
What juniors usually get wrong.
6
Close
When you pick this over the alternative.

Here's a short line you can speak, broken into clear beats:

Say this line

“Time is O(n) and space is O(1).”

Break into beats

TimeisOnandspace

Speaking order

2987408337471632900

Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.

Floyd's tortoise and hare: slow walks one, fast walks two they meet if a cycle exists.