Easy Linked List Question 37 of 224

How do you find the middle node of a linked list in one pass?

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

IdeaLinked List

HowWhat happens inside

Why they askShows real use

Slow pointer moves one step, fast moves 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
Slow pointer moves one
step, fast moves two
2
when fast hits the
end, slow is at the middle.
3
Time is O(n) and
extra space is O(1).
4
Counting length then walking
n/2 is two passes, which is fine but slower to code in an interview.
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 extra space is O(1).”

Break into beats

TimeisOnandextra

Speaking order

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

Slow pointer moves one step, fast moves two when fast hits the end, slow is at the middle.