23. Merge k Sorted Lists

23. Merge k Sorted Lists/Solution.cs

@@ -0,0 +1,29 @@
+public class Solution
+{
+    public ListNode? MergeKLists(ListNode[] lists)
+    {
+        ListNode? head = null;
+        ListNode? tail = null;
+        var queue = new PriorityQueue<ListNode, int>();
+        foreach (var l in lists)
+            if (l != null)
+                queue.Enqueue(l, l.val);
+        while (queue.Count > 0)
+        {
+            var l = queue.Dequeue();
+            if (head == null || tail == null)
+            {
+                head = l;
+                tail = l;
+            }
+            else
+            {
+                tail.next = l;
+                tail = l;
+            }
+            if (l.next != null)
+                queue.Enqueue(l.next, l.next.val);
+        }
+        return head;
+    }
+}