Add 23_Merge_k_Sorted_Lists.java

Author: Sean Prashad

K-way Merge/.gitkeep

@@ -0,0 +1,31 @@
+class Solution {
+ public ListNode mergeKLists(ListNode[] lists) {
+ if (lists == null || lists.length == 0) {
+ return null;
+ }
+
+ ListNode dummy = new ListNode(-1);
+ ListNode curr = dummy;
+
+ PriorityQueue<ListNode> pq = new PriorityQueue<>((l1, l2) -> l1.val - l2.val);
+
+ for (ListNode ln : lists) {
+ if (ln != null) {
+ pq.offer(ln);
+ }
+ }
+
+ while (!pq.isEmpty()) {
+ ListNode l = pq.poll();
+
+ if (l.next != null) {
+ pq.offer(l.next);
+ }
+
+ curr.next = l;
+ curr = curr.next;
+ }
+
+ return dummy.next;
+ }
+}