Create 0234_Palildrome_LL.java

Author: Daksh7112003

0234_Palildrome_LL.java

@@ -0,0 +1,55 @@
+ /*
+ * 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 boolean isPalindrome(ListNode head) {
+        if(head.next == null){
+            return true;
+        }
+        
+        ListNode middleNode = getMiddleNode(head);
+        ListNode head1 = head;
+        ListNode head2 = middleNode.next; 
+        middleNode.next = null; 
+        head2 = reverseLinkedList(head2); 
+
+        while(head1!=null && head2!=null){
+            if(head1.val != head2.val){
+                return false;
+            }
+            head1 = head1.next;
+            head2 = head2.next;
+        }
+
+        return true;
+    }
+
+    public ListNode getMiddleNode(ListNode node){
+        ListNode slow = node;
+        ListNode fast = node.next;
+
+        while(fast!=null && fast.next!=null){
+            slow = slow.next;
+            fast = fast.next.next;
+        }
+
+        return slow;
+    }
+
+    public ListNode reverseLinkedList(ListNode node){
+        if(node==null || node.next == null){
+            return node;
+        }
+
+        ListNode newHead = reverseLinkedList(node.next);
+        node.next.next = node;
+        node.next = null;
+        return newHead;
+    }
+}