Update Merge_K_SortedLinkedlist.java

yanglbme · web-flow · commit 4bc83966c303 · 2019-03-20T16:24:11.000+08:00
format code
diff --git a/DataStructures/Lists/Merge_K_SortedLinkedlist.java b/DataStructures/Lists/Merge_K_SortedLinkedlist.java
@@ -1,63 +1,54 @@
-import java.util.*;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.PriorityQueue;
 
+/**
+ * @author Arun Pandey (https://github.com/pandeyarun709)
+ */
 public class Merge_K_SortedLinkedlist {
-   
-   /*
-    * This function merge K sorted LinkedList
-    *  @param Node []a : array of LinkedList 
-    *  @param  int N  : size of array
-    *  
-    * author Arun Pandey (https://github.com/pandeyarun709)
-   */
-    Node mergeKList(Node[]a, int N)
-    {
+
+    /**
+     * This function merge K sorted LinkedList
+     *
+     * @param a array of LinkedList
+     * @param N size of array
+     * @return node
+     */
+    Node mergeKList(Node[] a, int N) {
         // Min Heap
-        PriorityQueue<Node> min = new PriorityQueue<>(new Comparator<Node>(){
-              
-              public int compare(Node x , Node y){
-                  return x.data - y.data;
-              } 
-        }); 
-        
+        PriorityQueue<Node> min = new PriorityQueue<>(Comparator.comparingInt(x -> x.data));
+
         // adding head of all linkedList in min heap
-        for(int i =0 ; i< N ;i++)
-        {
-            min.add(a[i]);
-        }
-        
+        min.addAll(Arrays.asList(a).subList(0, N));
+
         // Make new head among smallest heads in K linkedList 
         Node head = min.poll();
         min.add(head.next);
         Node curr = head;
 
-        //merging LinkedList
-        while(!min.isEmpty()) {
-            
+        // merging LinkedList
+        while (!min.isEmpty()) {
+
             Node temp = min.poll();
             curr.next = temp;
             curr = temp;
-            
-            //Add Node in min Heap only if temp.next is not null
-            if(temp.next != null){
+
+            // Add Node in min Heap only if temp.next is not null
+            if (temp.next != null) {
                 min.add(temp.next);
             }
         }
-        
-       return head;
-        
-   
-    }
-    
-    // Node Class
-    private  class Node{
-    	private int data;
-    	private Node next;
-    	
-    	public Node(int d)
-    	{
-    		this.data = d;
-    		next = null;
-    	}
+
+        return head;
     }
 
-}
+    private class Node {
+        private int data;
+        private Node next;
+
+        public Node(int d) {
+            this.data = d;
+            next = null;
+        }
+    }
+}
