HACKERRANK SOLUTION: Print in Reverse
import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;
public class Solution {
static class SinglyLinkedListNode {
public int data;
public SinglyLinkedListNode next;
public SinglyLinkedListNode(int nodeData) {
this.data = nodeData;
this.next = null;
}
}
static 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;
}
}
public static void printSinglyLinkedList(SinglyLinkedListNode node, String sep) {
while (node != null) {
System.out.print(node.data);
node = node.next;
if (node != null) {
System.out.print(sep);
}
}
}
// Complete the reversePrint function below.
static void reversePrint(SinglyLinkedListNode head) {
SinglyLinkedListNode cur = head;
SinglyLinkedListNode prev = null;
SinglyLinkedListNode next = null;
while(cur!=null)
{
next = cur.next;
cur.next = prev;
prev = cur;
cur = next;
}
head = prev;
while(head!=null)
{
System.out.println(head.data);
head=head.next;
}
}
private static final Scanner scanner = new Scanner(System.in);
public static void main(String[] args) {
int tests = scanner.nextInt();
scanner.skip(“(\r\n|[\n\r\u2028\u2029\u0085])?”);
for (int testsItr = 0; testsItr < tests; testsItr++) {
SinglyLinkedList llist = new SinglyLinkedList();
int llistCount = scanner.nextInt();
scanner.skip(“(\r\n|[\n\r\u2028\u2029\u0085])?”);
for (int i = 0; i < llistCount; i++) {
int llistItem = scanner.nextInt();
scanner.skip(“(\r\n|[\n\r\u2028\u2029\u0085])?”);
llist.insertNode(llistItem);
}
reversePrint(llist.head);
}
scanner.close();
}
}
import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;
public class Solution {
static class SinglyLinkedListNode {
public int data;
public SinglyLinkedListNode next;
public SinglyLinkedListNode(int nodeData) {
this.data = nodeData;
this.next = null;
}
}
static 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;
}
}
public static void printSinglyLinkedList(SinglyLinkedListNode node, String sep) {
while (node != null) {
System.out.print(node.data);
node = node.next;
if (node != null) {
System.out.print(sep);
}
}
}
// Complete the reversePrint function below.
/*
* For your reference:
*
* SinglyLinkedListNode {
* int data;
* SinglyLinkedListNode next;
* }
*
*/
static void reversePrint(SinglyLinkedListNode head) {
SinglyLinkedListNode cur = head;
SinglyLinkedListNode prev = null;
SinglyLinkedListNode next = null;
while(cur!=null)
{
next = cur.next;
cur.next = prev;
prev = cur;
cur = next;
}
head = prev;
while(head!=null)
{
System.out.println(head.data);
head=head.next;
}
}
private static final Scanner scanner = new Scanner(System.in);
public static void main(String[] args) {
int tests = scanner.nextInt();
scanner.skip(“(\r\n|[\n\r\u2028\u2029\u0085])?”);
for (int testsItr = 0; testsItr < tests; testsItr++) {
SinglyLinkedList llist = new SinglyLinkedList();
int llistCount = scanner.nextInt();
scanner.skip(“(\r\n|[\n\r\u2028\u2029\u0085])?”);
for (int i = 0; i < llistCount; i++) {
int llistItem = scanner.nextInt();
scanner.skip(“(\r\n|[\n\r\u2028\u2029\u0085])?”);
llist.insertNode(llistItem);
}
reversePrint(llist.head);
}
scanner.close();
}
}
