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

Return the sorted linked list that is the result of merging all of the individual linked lists.

Example 1:

Input: lists = [[1,2,4],[1,3,5],[3,6]]

Output: [1,1,2,3,3,4,5,6]

Example 2:

Input: lists = []

Output: []

Example 3:

Input: lists = [[]]

Output: []

Constraints:

• 0 <= lists.length <= 10000
• 0 <= lists[i].length <= 500
• -10000 <= lists[i][j] <= 10000
• lists[i] is sorted in ascending order.
• The sum of lists[i].length will not exceed 10000.