Added solution for reverse a linked list

Data-Structures/reverseLinkedList.java

@@ -0,0 +1,130 @@
+import java.io.*;
+import java.math.*;
+import java.security.*;
+import java.text.*;
+import java.util.*;
+import java.util.concurrent.*;
+import java.util.function.*;
+import java.util.regex.*;
+import java.util.stream.*;
+import static java.util.stream.Collectors.joining;
+import static java.util.stream.Collectors.toList;
+
+class SinglyLinkedListNode {
+    public int data;
+    public SinglyLinkedListNode next;
+
+    public SinglyLinkedListNode(int nodeData) {
+        this.data = nodeData;
+        this.next = null;
+    }
+}
+
+class SinglyLinkedList {
+    public SinglyLinkedListNode head;
+    public SinglyLinkedListNode tail;
+
+    public SinglyLinkedList() {
+        this.head = null;
+        this.tail = null;
+    }
+
+    public void insertNode(int nodeData) {
+        SinglyLinkedListNode node = new SinglyLinkedListNode(nodeData);
+
+        if (this.head == null) {
+            this.head = node;
+        } else {
+            this.tail.next = node;
+        }
+
+        this.tail = node;
+    }
+}
+
+class SinglyLinkedListPrintHelper {
+    public static void printList(SinglyLinkedListNode node, String sep, BufferedWriter bufferedWriter) throws IOException {
+        while (node != null) {
+            bufferedWriter.write(String.valueOf(node.data));
+
+            node = node.next;
+
+            if (node != null) {
+                bufferedWriter.write(sep);
+            }
+        }
+    }
+}
+
+class Result {
+
+    /*
+     * Complete the 'reverse' function below.
+     *
+     * The function is expected to return an INTEGER_SINGLY_LINKED_LIST.
+     * The function accepts INTEGER_SINGLY_LINKED_LIST llist as parameter.
+     */
+
+    /*
+     * For your reference:
+     *
+     * SinglyLinkedListNode {
+     *     int data;
+     *     SinglyLinkedListNode next;
+     * }
+     *
+     */
+
+    public static SinglyLinkedListNode reverse(SinglyLinkedListNode llist) {
+        SinglyLinkedListNode prev = null;
+        SinglyLinkedListNode current = llist;
+        SinglyLinkedListNode next = null;
+        while (current != null) {
+            next = current.next;
+            current.next = prev;
+            prev = current;
+            current = next;
+        }
+        llist = prev;
+        return llist;
+
+    }
+
+}
+
+public class Solution {
+    public static void main(String[] args) throws IOException {
+        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));
+
+        int tests = Integer.parseInt(bufferedReader.readLine().trim());
+
+        IntStream.range(0, tests).forEach(testsItr -> {
+            try {
+                SinglyLinkedList llist = new SinglyLinkedList();
+
+                int llistCount = Integer.parseInt(bufferedReader.readLine().trim());
+
+                IntStream.range(0, llistCount).forEach(i -> {
+                    try {
+                        int llistItem = Integer.parseInt(bufferedReader.readLine().trim());
+
+                        llist.insertNode(llistItem);
+                    } catch (IOException ex) {
+                        throw new RuntimeException(ex);
+                    }
+                });
+
+                SinglyLinkedListNode llist1 = Result.reverse(llist.head);
+
+                SinglyLinkedListPrintHelper.printList(llist1, " ", bufferedWriter);
+                bufferedWriter.newLine();
+            } catch (IOException ex) {
+                throw new RuntimeException(ex);
+            }
+        });
+
+        bufferedReader.close();
+        bufferedWriter.close();
+    }
+}

README.md

@@ -74,6 +74,7 @@ hackerrank solutions java GitHub | hackerrank tutorial in java | hackerrank 30 d
 |  Easy  | [Insert a Node at the Tail of a Linked List](https://www.hackerrank.com/challenges/insert-a-node-at-the-tail-of-a-linked-list/problem)| [Solution3.java](./Data-Structures/insertAtEndOfLinkedList.java)    									    |								[YT Video](https://youtu.be/KVTaQ0jy7Jw)
 |  Easy  | [Insert a node at a specific position in a linked list](https://www.hackerrank.com/challenges/insert-a-node-at-a-specific-position-in-a-linked-list/problem)| [Solution4.java](./Data-Structures/insertAtPositionOfLinkedList.java)    									    |				[YT Video](https://youtu.be/KVTaQ0jy7Jw)
 |  Easy  | [Compare two linked lists](https://www.hackerrank.com/challenges/compare-two-linked-lists/problem)| [Solution5.java](./Data-Structures/compare-two-linked-lists.java) |	[YT Video](https://youtu.be/KVTaQ0jy7Jw)
+|  Easy  | [Reverse a linked list](https://www.hackerrank.com/challenges/reverse-a-linked-list/problem)| [Solution6.java](./Data-Structures/reverseLinkedList.java)
 
 # Learning Resources
 1.) [Cracking the Coding Interview](https://amzn.to/3fH727G)