Merge K Sorted Arrays

Given k sorted arrays, merge them into one sorted array. Example: Input: lists = [[1, 4, 5], [1, 3, 4], [2, 6]] Output: [1, 1, 2, 3, 4, 4, 5, 6] Example Input [[1, 4, 5], [1, 3, 4], [2, 6]]