2 pointer

Author: Dhananjay Nagargoje

Diff for: out/production/main/problems/ontwopointerstrategy/BinaryArraySorting.class

@@ -1,4 +1,71 @@
 package problems.patterns.onlinkedlistreversal;
 
-public class ReverseLinkedList {
+class ListNode {
+    int value = 0;
+    ListNode next;
+
+    ListNode(int value) {
+        this.value = value;
+    }
 }
+
+class ReverseLinkedList {
+
+    public static ListNode reverse(ListNode head) {
+      if (head == null || head.next == null) return head;
+
+      ListNode prev = null;
+      ListNode cur = head;
+
+      while (cur != null) {
+          ListNode rest = cur.next;
+          cur.next = prev;
+          prev = cur;
+          cur = rest;
+      }
+      return prev;
+    }
+    public static ListNode reverse(ListNode head, int p, int q) {
+        if (head == null || head.next == null) return head;
+        if (p == 1 && q == 1) return head;
+        int cnt = 1;
+        ListNode rethead = head;
+        ListNode prevh = null;
+
+        while (cnt!=p) {
+            prevh = head;
+            head = head.next;
+            cnt++;
+        }
+        ListNode prev = null;
+        ListNode cur = head;
+        ListNode rest = cur.next;
+        ListNode temphead = head;
+        while (cnt<= q && cur != null) {
+            rest = cur.next;
+            cur.next = prev;
+            prev = cur;
+            cur = rest;
+            cnt++;
+        }
+        prevh.next = prev;
+        temphead.next = rest;
+        return prevh;
+    }
+
+    public static void main(String[] args) {
+        ListNode head = new ListNode(2);
+        head.next = new ListNode(4);
+        head.next.next = new ListNode(6);
+        head.next.next.next = new ListNode(8);
+        head.next.next.next.next = new ListNode(10);
+
+      //  ListNode result = ReverseLinkedList.reverse(head);
+        ListNode result = ReverseLinkedList.reverse(head, 2, 4);
+        System.out.print("Nodes of the reversed LinkedList are: ");
+        while (result != null) {
+            System.out.print(result.value + " ");
+            result = result.next;
+        }
+    }
+}

Diff for: out/production/main/problems/ontwopointerstrategy/DeleteMiddleOfList.class

@@ -1,4 +1,4 @@
-package problems.ontwopointerstrategy;
+package problems.patterns.ontwopointerstrategy;
 
 public class BinaryArraySorting {
     /**

Diff for: out/production/main/problems/ontwopointerstrategy/TripLetWithZeroSum.class

@@ -1,4 +1,4 @@
-package problems.ontwopointerstrategy;
+package problems.patterns.ontwopointerstrategy;
 
 import java.util.Arrays;