Merge k Sorted Lists

Difficulty

Hard

Question

You are given an array of k linked-lists lists, each linked-list is sorted in ascending order.

Merge all the linked-lists into one sorted linked-list and return it.

Example 1:

Input: lists = [[1,4,5],[1,3,4],[2,6]]
Output: [1,1,2,3,4,4,5,6]
Explanation: The linked-lists are:
[
1->4->5,
1->3->4,
2->6
]
merging them into one sorted list:
1->1->2->3->4->4->5->6

Example 2:

Input: lists = []
Output: []

Example 3:

Input: lists = [[]]
Output: []

Constraints:

`k == lists.length`
`0 <= k <= 10^4`
`0 <= lists[i].length <= 500`
`-10^4 <= lists[i][j] <= 10^4`
`lists[i]` is sorted in ascending order.
The sum of `lists[i].length` will not exceed `10^4`.

Link

Merge k Sorted Lists

Solution

Solution uses priority queue with custom comparator to store nodes in proper order and rewrites their order.

Stats

Metric	Value
Runtime	0 ms - beats 100%
Memory	18.44 MB - beats 63.78%