High Hashing Question 148 of 224

How do you copy a linked list where each node has a random pointer?

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

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First pass: hash original node to a cloned node with the same value.

Why interviewers care about Hashing:

This is a process

question about Hashing.

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
First pass: hash original
node to a cloned node with the same value.
2
Second pass: set clone.next
and clone.random via the map.
3
Time is O(n) and
space is O(n).
4
An interleaving trick (insert
clones next to originals, wire random, then split) achieves O(1) extra space.
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(n).”

Break into beats

TimeisOnandspace

Speaking order

2987408337471632900

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

First pass: hash original node to a cloned node with the same value. Second pass: set clone.next and clone.random via the map.