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A2Z Sheet

272. Merge K sorted Lists

Hard
Step 11: Heaps [Learning, Medium, Hard Problems]›Medium Problems

Merge K sorted Lists

HardFunction: mergeKSortedLists()
ASCI Mission Breakdown • Simple as Hell
"Master Merge K sorted Lists: Take `nums` (number[]), execute an optimal medium problems strategy, and return number[] with clean edge-case handling."
Real-World Metaphor:

Think of Merge K sorted Lists as an everyday real-world challenge: you receive input data, inspect its elements in sequence without making unnecessary duplicate passes, and transform the collection to reach the exact target without wasting computer memory.

Interactive Visual WalkthroughARRAY-POINTERS
Step 1 / 3
Merge K sorted Lists State Pipeline
start
5
[0]
2
[1]
3
[2]
1
[3]
Memory Notepad / State Tracker
Status:Initialized
Mode:Scanning
Evaluating

1. Initialize State for Merge K sorted Lists

Load inputs and initialize algorithmic registers.

How to Think About This (Mental Model)

  1. Unpack the problem parameters (`nums` (number[])) and clarify what is given vs what must be returned.
  2. Identify the optimal data structure or pattern (e.g. pointers, hash map, or stack) to avoid redundant recalculations.
  3. Walk through state transitions, handle edge cases (empty collections, single items, negative numbers), and return the verified result.

Given an array of integers `nums`, sort the array in ascending order using the **Merge K sorted Lists** technique. Return the sorted array.

Examples

Example 1
Input: nums = [5,2,3,1]
Output: [1,2,3,5]
Example 2
Input: nums = [5,1,1,2,0,0]
Output: [0,0,1,1,2,5]

Constraints

  • 1 <= nums.length <= 5 * 10^4
  • -5 * 10^4 <= nums[i] <= 5 * 10^4
Topic Tags:
Heaps [Learning, Medium, Hard Problems]Medium ProblemsmergeKSortedLists
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