From 0a143dc74387fd140269d89a9aaab60dc4cf4d59 Mon Sep 17 00:00:00 2001
From: Saikat Kar <saikat16th@gmail.com>
Date: Tue, 4 Jan 2022 23:49:14 +0530
Subject: [PATCH] Time: 8 ms (31.10%), Space: 44.2 MB (17.47%) - LeetHub

---
 .../23-merge-k-sorted-lists.java              | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 23-merge-k-sorted-lists/23-merge-k-sorted-lists.java

diff --git a/23-merge-k-sorted-lists/23-merge-k-sorted-lists.java b/23-merge-k-sorted-lists/23-merge-k-sorted-lists.java
new file mode 100644
index 0000000..434533a
--- /dev/null
+++ b/23-merge-k-sorted-lists/23-merge-k-sorted-lists.java
@@ -0,0 +1,40 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+    public ListNode mergeKLists(ListNode[] lists) {
+        Comparator<ListNode> cmp;
+        cmp = new Comparator<ListNode>() {  
+        @Override
+        public int compare(ListNode o1, ListNode o2) {
+            // TODO Auto-generated method stub
+            return o1.val-o2.val;
+        }
+        };
+        Queue<ListNode> pq = new PriorityQueue<>(cmp);
+        ListNode mergedHead = new ListNode();
+        ListNode result = mergedHead;
+        for (ListNode ln : lists) {
+            if(ln != null) {
+                pq.add(ln);  
+            }
+        }
+        while (!pq.isEmpty()) {
+            ListNode min = pq.poll();
+            mergedHead.next = min;
+            mergedHead = mergedHead.next;
+            if (min.next != null) {
+                min = min.next;
+                pq.add(min);
+            }
+        }
+        return result.next;
+    }
+}
\ No newline at end of file