Merge K Sorted Lists

You are given an array of k linked lists lists, where each list is sorted in ascending order. Examples Example 1: Input: lists = [[1,4,5],[1,3,4],[2,6]] Output: [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.