Merge pull request #596 from Aarush2k1/patch-1

Leetcode 23: Merge k sorted linked lists

Author: gantavyamalviya

Java/Leetcode/Leetcode23.java

@@ -0,0 +1,27 @@
+/*
+You are given an array of k linked-lists lists, each linked-list is sorted in ascending order.
+Merge all the linked-lists into one sorted linked-list and return it.
+Input: lists = [[1,4,5],[1,3,4],[2,6]]
+Output: [1,1,2,3,4,4,5,6]
+*/
+class Solution {
+    public ListNode mergeKLists(ListNode[] lists) {
+        PriorityQueue<ListNode> q=new PriorityQueue<>((a,b)->a.val-b.val);
+        ListNode curr=new ListNode(0);
+        ListNode ans=curr;
+        
+        for(ListNode l:lists){
+            while(l!=null){
+                q.offer(l);
+                l=l.next;
+            }
+        }
+        
+        while(!q.isEmpty()){
+            curr.next=q.poll();
+            curr=curr.next;
+            curr.next=null;
+        }
+        return ans.next;
+    }
+}