From 4d06c5f6ba8a9563c0eb961ffd066e800edf5afa Mon Sep 17 00:00:00 2001
From: Ranjan Mohanty <ranjanmohanty@outlook.in>
Date: Tue, 12 Oct 2021 10:49:21 +0530
Subject: [PATCH] Add remove duplicate nodes from a sorted linked list
 algorithm (#2452)

---
 .../Lists/RemoveDuplicateNodes.java           | 53 +++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 DataStructures/Lists/RemoveDuplicateNodes.java

diff --git a/DataStructures/Lists/RemoveDuplicateNodes.java b/DataStructures/Lists/RemoveDuplicateNodes.java
new file mode 100644
index 000000000..4eb12de29
--- /dev/null
+++ b/DataStructures/Lists/RemoveDuplicateNodes.java
@@ -0,0 +1,53 @@
+package DataStructures.Lists;
+
+import DataStructures.Lists.Node;
+
+public class RemoveDuplicateNodes {
+
+    public Node deleteDuplicates(Node head) {
+        // sentinel
+        Node sentinel = new Node(0, head);
+
+        // predecessor = the last node 
+        // before the sublist of duplicates
+        Node pred = sentinel;
+
+        while (head != null) {
+            // if it's a beginning of duplicates sublist 
+            // skip all duplicates
+            if (head.next != null && head.value == head.next.value) {
+                // move till the end of duplicates sublist
+                while (head.next != null && head.value == head.next.value) {
+                    head = head.next;
+                }
+                // skip all duplicates
+                pred.next = head.next;
+                // otherwise, move predecessor
+            } else {
+                pred = pred.next;
+            }
+
+            // move forward
+            head = head.next;
+        }
+        return sentinel.next;
+    }
+
+    public void print(Node head) {
+        Node temp = head;
+        while (temp != null && temp.next != null) {
+            System.out.print(temp.value + "->");
+            temp = temp.next;
+        }
+        if (temp != null) {
+            System.out.print(temp.value);
+        }
+    }
+
+    public static void main(String arg[]) {
+        RemoveDuplicateNodes instance = new RemoveDuplicateNodes();
+        Node head = new Node(0, new Node(2, new Node(3, new Node(3, new Node(4)))));
+        head = instance.deleteDuplicates(head);
+        instance.print(head);
+    }
+}
\ No newline at end of file