Merge k Sorted Lists
You are given an array of k linked lists, where each linked list is sorted in ascending order.
Merge all the linked lists into one sorted linked list and return its head.
Example 1
Input
lists = [[1,4,5],[1,3,4],[2,6]]
Output
[1,1,2,3,4,4,5,6]
Explanation
All three sorted lists are merged into one sorted list.
Example 2
Input
lists = []
Output
[]
Explanation
There are no linked lists to merge, so the result is empty.
Constraints
Hints:
Hint 1
Use a min-heap to keep track of the smallest current element from each list.
Hint 2
Insert the first node of every non-empty list into the heap.
Author & Technical Reviewer
Technically reviewed by: ExamAdda Technical Review Team
Technical Reviewers, ExamAdda
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Published
Aug 10, 2026
Last updated
Aug 11, 2026
Content Verification Methodology
Definitions and complexity claims were checked against authoritative computer-science references. Code examples were compiled and tested with standard, boundary and edge-case inputs.
Expected Output