51. Merge K Sorted Lists

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Input: lists = [[1,4,5],[1,3,4],[2,6]] (represented as linked lists)

Output: [1,1,2,3,4,4,5,6] (represented as a linked list)

Explanation: The three sorted lists are merged into a single sorted list.

Input: lists = []

Output: []

Explanation: An empty list of lists results in an empty merged list.

Input: lists = [[]]

Output: []

Explanation: A list containing an empty list results in an empty merged list.

Time Complexity

O(N log k)

Space Complexity

O(k)