public ListNode MergeKLists(ListNode[] lists)
{
var pq = new MinHeap();
foreach (var node in lists)
{
if (node != null)
{
pq.Add(node.val, node);
}
}
ListNode head = null;
ListNode curr = null;
while (pq.map.Any())
{
var node = pq.PopMin();
if (node.next != null)
{
pq.Add(node.next.val, node.next);
}
if (curr == null)
{
head = node;
head = curr;
}
else
{
curr.next = node;
curr = curr.next;
}
}
return(head);
}