Merge K Sorted Lists

Author: TonyKim9401

merge-k-sorted-lists/TonyKim9401.java

@@ -0,0 +1,30 @@
+// TC: O(n * log m)
+// m -> the number of the lists, n -> the number of node
+// SC: O(m)
+// m -> the number of the lists (max m)
+class Solution {
+    public ListNode mergeKLists(ListNode[] lists) {
+        if (lists == null || lists.length == 0) return null;
+
+        PriorityQueue<ListNode> pq = new PriorityQueue<>((a, b) -> a.val - b.val);
+
+        for (ListNode node : lists) {
+            if (node != null) pq.offer(node);
+        }
+
+        ListNode dummy = new ListNode(0);
+        ListNode current = dummy;
+
+        while (!pq.isEmpty()) {
+            ListNode minNode = pq.poll();
+            current.next = minNode;
+            current = current.next;
+
+            if (minNode.next != null) {
+                pq.offer(minNode.next);
+            }
+        }
+
+        return dummy.next;
+    }
+}