void minHeapify(ArrayList<ListNode> lists, int heapsize, int index) {
			int min = index;

			if (index * 2 + 1 < heapsize
					&& lists.get(index * 2 + 1).val < lists.get(min).val) {
				min = (index * 2 + 1);
			}

			if (index * 2 + 2 < heapsize
					&& lists.get(index * 2 + 2).val < lists.get(min).val) {
				min = (index * 2 + 2);
			}

			if (min != index) {
				ListNode tmp = lists.get(index);
				lists.set(index, lists.get(min));
				lists.set(min, tmp);
				minHeapify(lists, heapsize, min);
			}

		}