High Heap Question 170 of 224

How do you merge k sorted arrays into one sorted array?

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

Working folderYour files

Staginggit add

Local repogit commit

Remotegit push

Min-heap of the current head of each array with (value, array_id, index).

Why interviewers care about Heap:

This is a process

question about Heap.

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
Min-heap of the current
head of each array with (value, array_id, index).
2
Pop and push the
next element from that array.
3
Time is O(N log
k) for N total elements and space is O(k) plus the output.
4
Concatenate-and-sort is O(N log
N) and ignores the sorted runs.
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 log k) for N total elements and space is O(k) plus the output.”

Break into beats

TimeisONlogk

Speaking order

2987408337471632900

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

Min-heap of the current head of each array with (value, array_id, index). Pop and push the next element from that array.