Reverse every k nodes of a linked list: 1st commit

Author: paulsagar1a

linkedlist/ReverseEveryKNodes.java

@@ -0,0 +1,78 @@
+/************************************************************************
+ * @author SAGAR PAUL (paulsagar1a)
+ * @category Linked list
+ * 
+ * Reverse every k nodes of a linked list
+ * Given a linked list and a number k. Reverse every k nodes in the list. 
+ * Example : Input 1->2->3->4->5->6 and k = 2 Output 2->1->4->3->6->5
+ ************************************************************************/
+package linkedlist;
+
+public class ReverseEveryKNodes {
+	public Node head;
+	public static class Node {
+		int data;
+		Node next;
+		public Node(int data) {
+			this.data = data;
+		}
+	}
+	public void addNode(Node node) {
+		if(head == null) {
+			head = node;
+		} else {
+			Node temp = head;
+			while(temp.next != null) {
+				temp = temp.next;
+			}
+			temp.next = node;
+		}
+	}
+	
+	public void print() {
+		Node temp = head;
+		while(temp != null) {
+			System.out.println(temp.data);
+			temp = temp.next;
+		}
+	}
+	
+	public void reverseEveryKNodes(int k) {
+		head = reverseKNodes(head, k);
+	}
+	
+	public Node reverseKNodes(Node head, int k) {
+		int i = 0;
+		Node current = head;
+		Node next = null, previous = null;
+		while(current != null && i<k) {
+			next = current.next;
+			current.next = previous;
+			previous = current;
+			current = next;
+			i++;
+		}
+		if(next != null)
+			head.next = reverseKNodes(next, k);
+		return previous;
+	}
+	
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		ReverseEveryKNodes obj = new ReverseEveryKNodes();
+		obj.addNode(new Node(1));
+		obj.addNode(new Node(2));
+		obj.addNode(new Node(3));
+		obj.addNode(new Node(4));
+		obj.addNode(new Node(5));
+		obj.addNode(new Node(6));
+		obj.addNode(new Node(7));
+		obj.addNode(new Node(8));
+		System.out.println("----------Before----------");
+		obj.print();
+		obj.reverseEveryKNodes(3);
+		System.out.println("----------After----------");
+		obj.print();
+	}
+
+}