Given a XOR linked list and an integer N, the task is to print the Nth node from the end of the given XOR linked list.
Examples:
Input: 4 –> 6 –> 7 –> 3, N = 1
Output: 3
Explanation: 1st node from the end is 3.
Input: 5 –> 8 –> 9, N = 4
Output: Wrong Input
Explanation: The given Xor Linked List contains only 3 nodes.
Approach: Follow the steps below to solve the problem:
- Traverse the first N nodes of the Linked List using a pointer, say curr.
- Use another pointer, say curr1, and traverse the linked list incrementing curr and curr1 by a node after every iteration.
- Iterate until the pointer curr exceeds the end of the List, i.e.NULL. Once reached, print the value of the node curr1 as the required answer.
Below is the implementation of the above approach:
C++
// C++ program to implement // the above approach #include <bits/stdc++.h> #include <inttypes.h> using namespace std;
// Structure of a node // in XOR linked list struct Node {
// Stores data value
// of a node
int data;
// Stores XOR of previous
// pointer and next pointer
struct Node* nxp;
}; // Function to find the XOR of two nodes struct Node* XOR( struct Node* a, struct Node* b)
{ return ( struct Node*)(( uintptr_t )(a) ^ ( uintptr_t )(b));
} // Function to insert a node with // given value at given position struct Node* insert( struct Node** head, int value)
{ // If XOR linked list is empty
if (*head == NULL) {
// Initialize a new Node
struct Node* node = new Node;
// Stores data value in
// the node
node->data = value;
// Stores XOR of previous
// and next pointer
node->nxp = XOR(NULL, NULL);
// Update pointer of head node
*head = node;
}
// If the XOR linked list
// is not empty
else {
// Stores the address
// of current node
struct Node* curr = *head;
// Stores the address
// of previous node
struct Node* prev = NULL;
// Initialize a new Node
struct Node* node
= new Node();
// Update curr node address
curr->nxp = XOR(node, XOR(NULL, curr->nxp));
// Update new node address
node->nxp = XOR(NULL, curr);
// Update head
*head = node;
// Update data value of
// current node
node->data = value;
}
return *head;
} // Function to print elements of // the XOR Linked List void printList( struct Node** head)
{ // Stores XOR pointer
// in current node
struct Node* curr = *head;
// Stores XOR pointer of
// in previous Node
struct Node* prev = NULL;
// Stores XOR pointer of
// in next node
struct Node* next;
// Traverse XOR linked list
while (curr != NULL) {
// Print current node
cout << curr->data << " " ;
// Forward traversal
next = XOR(prev, curr->nxp);
// Update prev
prev = curr;
// Update curr
curr = next;
}
} struct Node* NthNode( struct Node** head, int N)
{ int count = 0;
// Stores XOR pointer
// in current node
struct Node* curr = *head;
struct Node* curr1 = *head;
// Stores XOR pointer of
// in previous Node
struct Node* prev = NULL;
struct Node* prev1 = NULL;
// Stores XOR pointer of
// in next node
struct Node* next;
struct Node* next1;
while (count < N && curr != NULL) {
// Forward traversal
next = XOR(prev, curr->nxp);
// Update prev
prev = curr;
// Update curr
curr = next;
count++;
}
if (curr == NULL && count < N) {
cout << "Wrong Input\n" ;
return ( uintptr_t )0;
}
else {
while (curr != NULL) {
// Forward traversal
next = XOR(prev, curr->nxp);
next1 = XOR(prev1, curr1->nxp);
// Update prev
prev = curr;
prev1 = curr1;
// Update curr
curr = next;
curr1 = next1;
}
cout << curr1->data << " " ;
}
} // Driver Code int main()
{ /* Create following XOR Linked List
head -->7 –> 6 –>8 –> 11 –> 3 –> 1 –> 2 –> 0*/
struct Node* head = NULL;
insert(&head, 0);
insert(&head, 2);
insert(&head, 1);
insert(&head, 3);
insert(&head, 11);
insert(&head, 8);
insert(&head, 6);
insert(&head, 7);
NthNode(&head, 3);
return (0);
} |
C
// C program to implement // the above approach #include <inttypes.h> #include <stdio.h> #include <stdlib.h> // Structure of a node // in XOR linked list struct Node {
// Stores data value
// of a node
int data;
// Stores XOR of previous
// pointer and next pointer
struct Node* nxp;
}; // Function to find the XOR of two nodes struct Node* XOR( struct Node* a,
struct Node* b)
{ return ( struct Node*)(( uintptr_t )(a)
^ ( uintptr_t )(b));
} // Function to insert a node with // given value at given position struct Node* insert(
struct Node** head, int value)
{ // If XOR linked list is empty
if (*head == NULL) {
// Initialize a new Node
struct Node* node
= ( struct Node*) malloc (
sizeof ( struct Node));
// Stores data value in
// the node
node->data = value;
// Stores XOR of previous
// and next pointer
node->nxp = XOR(NULL, NULL);
// Update pointer of head node
*head = node;
}
// If the XOR linked list
// is not empty
else {
// Stores the address
// of current node
struct Node* curr = *head;
// Stores the address
// of previous node
struct Node* prev = NULL;
// Initialize a new Node
struct Node* node
= ( struct Node*) malloc (
sizeof ( struct Node));
// Update curr node address
curr->nxp = XOR(node,
XOR(NULL, curr->nxp));
// Update new node address
node->nxp = XOR(NULL, curr);
// Update head
*head = node;
// Update data value of
// current node
node->data = value;
}
return *head;
} // Function to print elements of // the XOR Linked List void printList( struct Node** head)
{ // Stores XOR pointer
// in current node
struct Node* curr = *head;
// Stores XOR pointer of
// in previous Node
struct Node* prev = NULL;
// Stores XOR pointer of
// in next node
struct Node* next;
// Traverse XOR linked list
while (curr != NULL) {
// Print current node
printf ( "%d " , curr->data);
// Forward traversal
next = XOR(prev, curr->nxp);
// Update prev
prev = curr;
// Update curr
curr = next;
}
} struct Node* NthNode( struct Node** head,
int N)
{ int count = 0;
// Stores XOR pointer
// in current node
struct Node* curr = *head;
struct Node* curr1 = *head;
// Stores XOR pointer of
// in previous Node
struct Node* prev = NULL;
struct Node* prev1 = NULL;
// Stores XOR pointer of
// in next node
struct Node* next;
struct Node* next1;
while (count < N && curr != NULL) {
// Forward traversal
next = XOR(prev, curr->nxp);
// Update prev
prev = curr;
// Update curr
curr = next;
count++;
}
if (curr == NULL && count < N) {
printf ( "Wrong Input" );
return ( uintptr_t )0;
}
else {
while (curr != NULL) {
// Forward traversal
next = XOR(prev,
curr->nxp);
next1 = XOR(prev1,
curr1->nxp);
// Update prev
prev = curr;
prev1 = curr1;
// Update curr
curr = next;
curr1 = next1;
}
printf ( "%d" , curr1->data);
}
} // Driver Code int main()
{ /* Create following XOR Linked List
head -->7 –> 6 –>8 –> 11 –> 3 –> 1 –> 2 –> 0*/
struct Node* head = NULL;
insert(&head, 0);
insert(&head, 2);
insert(&head, 1);
insert(&head, 3);
insert(&head, 11);
insert(&head, 8);
insert(&head, 6);
insert(&head, 7);
NthNode(&head, 3);
return (0);
} |
Java
import java.util.*;
// Structure of a node in XOR linked list class Node {
int value;
int npx;
Node( int value) {
this .value = value;
this .npx = 0 ;
}
} // XorLinkedList class class XorLinkedList {
private Node head;
private Node tail;
private List<Node> nodes;
// Constructor
public XorLinkedList() {
this .head = null ;
this .tail = null ;
this .nodes = new ArrayList<>();
}
// Function to insert a node with given value at the beginning
public void insert( int value) {
// Initialize a new Node
Node node = new Node(value);
// Check If XOR linked list is empty
if (head == null ) {
// Update pointer of head node
head = node;
// Update pointer of tail node
tail = node;
} else {
// Update curr node address
head.npx = System.identityHashCode(node) ^ head.npx;
// Update new node address
node.npx = System.identityHashCode(head);
// Update head
head = node;
}
// push node
nodes.add(node);
}
// Method to get length of linked list
public int length() {
if (!isEmpty()) {
int prevId = 0 ;
Node node = head;
int nextId = 1 ;
int count = 1 ;
while (nextId != 0 ) {
nextId = prevId ^ node.npx;
if (nextId != 0 ) {
prevId = System.identityHashCode(node);
node = typeCast(nextId);
count++;
} else {
return count;
}
}
} else {
return 0 ;
}
return 0 ;
}
// Method to get the Nth node value
public void nthNode( int N) {
int count = 1 ;
int prevId = 0 ;
int prev1Id = 0 ;
Node node = head;
Node node1 = head;
int nextId = 1 ;
int next1Id = 1 ;
while (nextId != 0 && count < N) {
nextId = prevId ^ node.npx;
if (nextId != 0 ) {
prevId = System.identityHashCode(node);
node = typeCast(nextId);
count++;
} else {
System.out.println( "Wrong Input" );
return ;
}
}
nextId = prevId ^ node.npx;
prevId = System.identityHashCode(node);
node = typeCast(nextId);
if (nextId == 0 && count < N) {
System.out.println( "Wrong Input" );
return ;
}
while (nextId != 0 ) {
nextId = prevId ^ node.npx;
next1Id = prev1Id ^ node1.npx;
if (nextId != 0 ) {
prevId = System.identityHashCode(node);
node = typeCast(nextId);
}
if (nextId != 0 ) {
prev1Id = System.identityHashCode(node1);
node1 = typeCast(next1Id);
}
}
node1 = typeCast(next1Id);
System.out.println(node1.value);
}
// Function to print elements of the XOR Linked List
public void printList() {
if (head != null ) {
int prevId = 0 ;
Node node = head;
int nextId = 1 ;
System.out.print(node.value + " " );
while (nextId != 0 ) {
nextId = prevId ^ node.npx;
if (nextId != 0 ) {
prevId = System.identityHashCode(node);
node = typeCast(nextId);
System.out.print(node.value + " " );
} else {
return ;
}
}
}
}
// Method to check if the linked list is empty or not
public boolean isEmpty() {
return head == null ;
}
// Method to return a new instance of type
private Node typeCast( int id) {
for (Node n : nodes) {
if (System.identityHashCode(n) == id) {
return n;
}
}
return null ;
}
} // Main class public class Main {
public static void main(String[] args) {
// Create XOR linked list
XorLinkedList xorLinkedList = new XorLinkedList();
// Insert elements into XOR linked list
xorLinkedList.insert( 0 );
xorLinkedList.insert( 2 );
xorLinkedList.insert( 1 );
xorLinkedList.insert( 3 );
xorLinkedList.insert( 11 );
xorLinkedList.insert( 8 );
xorLinkedList.insert( 6 );
xorLinkedList.insert( 7 );
// Get the Nth node value
xorLinkedList.nthNode( 3 );
}
} |
C#
// C# program for the above approach using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
// Structure of a node in XOR linked list class Node {
public int value;
public int npx;
public Node( int value)
{
this .value = value;
this .npx = 0;
}
} // XorLinkedList class class XorLinkedList {
private Node head;
private List<Node> nodes;
// Constructor
public XorLinkedList()
{
this .head = null ;
this .nodes = new List<Node>();
}
// Function to insert a node with given value at the
// beginning
public void Insert( int value)
{
// Initialize a new Node
Node node = new Node(value);
// Check If XOR linked list is empty
if (head == null ) {
// Update pointer of head node
head = node;
}
else {
// Update curr node address
head.npx = RuntimeHelpers.GetHashCode(node)
^ head.npx;
// Update new node address
node.npx = RuntimeHelpers.GetHashCode(head);
// Update head
head = node;
}
// push node
nodes.Add(node);
}
// Method to get length of linked list
public int Length()
{
if (!IsEmpty()) {
int prevId = 0;
Node node = head;
int nextId = 1;
int count = 1;
while (nextId != 0) {
nextId = prevId ^ node.npx;
if (nextId != 0) {
prevId
= RuntimeHelpers.GetHashCode(node);
node = TypeCast(nextId);
count++;
}
else {
return count;
}
}
}
else {
return 0;
}
return 0;
}
// Method to get the Nth node value
public void NthNode( int N)
{
int count = 1;
int prevId = 0;
int prev1Id = 0;
Node node = head;
Node node1 = head;
int nextId = 1;
int next1Id = 1;
while (nextId != 0 && count < N) {
nextId = prevId ^ node.npx;
if (nextId != 0) {
prevId = RuntimeHelpers.GetHashCode(node);
node = TypeCast(nextId);
count++;
}
else {
Console.WriteLine( "Wrong Input" );
return ;
}
}
nextId = prevId ^ node.npx;
prevId = RuntimeHelpers.GetHashCode(node);
node = TypeCast(nextId);
if (nextId == 0 && count < N) {
Console.WriteLine( "Wrong Input" );
return ;
}
while (nextId != 0) {
nextId = prevId ^ node.npx;
next1Id = prev1Id ^ node1.npx;
if (nextId != 0) {
prevId = RuntimeHelpers.GetHashCode(node);
node = TypeCast(nextId);
}
if (nextId != 0) {
prev1Id = RuntimeHelpers.GetHashCode(node1);
node1 = TypeCast(next1Id);
}
}
node1 = TypeCast(next1Id);
Console.WriteLine(node1.value);
}
// Function to print elements of the XOR Linked List
public void PrintList()
{
if (head != null ) {
int prevId = 0;
Node node = head;
int nextId = 1;
Console.Write(node.value + " " );
while (nextId != 0) {
nextId = prevId ^ node.npx;
if (nextId != 0) {
prevId
= RuntimeHelpers.GetHashCode(node);
node = TypeCast(nextId);
Console.Write(node.value + " " );
}
else {
return ;
}
}
}
}
// Method to check if the linked list is empty or not
public bool IsEmpty() { return head == null ; }
// Method to return a new instance of type
private Node TypeCast( int id)
{
foreach (Node n in nodes)
{
if (RuntimeHelpers.GetHashCode(n) == id) {
return n;
}
}
return null ;
}
} // Main class public class GFG {
public static void Main( string [] args)
{
// Create XOR linked list
XorLinkedList xorLinkedList = new XorLinkedList();
// Insert elements into XOR linked list
xorLinkedList.Insert(0);
xorLinkedList.Insert(2);
xorLinkedList.Insert(1);
xorLinkedList.Insert(3);
xorLinkedList.Insert(11);
xorLinkedList.Insert(8);
xorLinkedList.Insert(6);
xorLinkedList.Insert(7);
// Get the Nth node value
xorLinkedList.NthNode(3);
}
} // This code is contributed by Susobhan Akhuli |
Javascript
// Javascript program for the above approach // Structure of a node in XOR linked list class Node { constructor(d) {
this .data = d;
this .npx = null ;
}
} // XorLinkedList class class XorLinkedList { // constructor
constructor() {
this .head = null ;
}
// Function to insert a node with given value at given position
insert(data) {
// Initialize a new Node
const newNode = new Node(data);
newNode.npx = this .head;
this .head = newNode;
}
// method to get length of linked list
length() {
let count = 0;
let nextId = this .head;
while (nextId!== null ) {
nextId = nextId.npx;
count += 1;
}
return count;
}
// Method to get the Nth node data
nthNode(N) {
let count = this .length();
if (N > count){
console.log( "Wrong Input" );
return ;
}
count -= N;
let nextId = this .head;
while (count > 0) {
nextId = nextId.npx;
count-=1;
}
console.log(nextId.data);
}
// Function to print elements of the XOR Linked List
printList() {
let temp = this .head;
while (temp !== null ) {
console.log(temp.data + " " );
temp = temp.npx;
}
console.log();
}
// method to check if the linked list is empty or not
isEmpty(nod) {
if (nod === null ) {
return true ;
}
return false ;
}
} // Create XOR linked list const head = new XorLinkedList();
// Insert elements into XOR linked list head.insert(0); head.insert(2); head.insert(1); head.insert(3); head.insert(11); head.insert(8); head.insert(6); head.insert(7); // Get the Nth node data head.nthNode(3); // This code is contributed by Susobhan Akhuli |
Python3
# Python implementation of the above approach. import ctypes
# Structure of a node in XOR linked list class Node:
def __init__( self , value):
self .value = value
self .npx = 0
# create linked list class class XorLinkedList:
# constructor
def __init__( self ):
self .head = None
self .tail = None
self .__nodes = []
# Function to insert a node with given value at given position
def insert( self , value):
# Initialize a new Node
node = Node(value)
# Check If XOR linked list is empty
if self .head is None :
# Update pointer of head node
self .head = node
# Update pointer of tail node
self .tail = node
else :
# Update curr node address
self .head.npx = id (node) ^ self .head.npx
# Update new node address
node.npx = id ( self .head)
# Update head
self .head = node
# push node
self .__nodes.append(node)
# method to get length of linked list
def Length( self ):
if not self .isEmpty():
prev_id = 0
node = self .head
next_id = 1
count = 1
while next_id:
next_id = prev_id ^ node.npx
if next_id:
prev_id = id (node)
node = self .__type_cast(next_id)
count + = 1
else :
return count
else :
return 0
def NthNode( self , N):
count = 1
# Stores XOR pointer of
# in previous Node
prev_id = 0
prev1_id = 0
# Stores XOR pointer
# in current node
node = self .head
node1 = self .head
# Stores XOR pointer of
# in next node
next_id = 1
next1_id = 1
while (next_id and count < N):
# Forward traversal
next_id = prev_id ^ node.npx
if next_id:
# Update prev
prev_id = id (node)
# Update curr
node = self .__type_cast(next_id)
count = count + 1
# Move 1 step forward because in python, prev1_id and next1_id are
# starting from 0 and 1 respectively, and not with None.
next_id = prev_id ^ node.npx
prev_id = id (node)
node = self .__type_cast(next_id)
if not next_id and count < N:
print ( "Wrong Input" )
return
while next_id:
# Forward Traversal
next_id = prev_id ^ node.npx
next1_id = prev1_id ^ node1.npx
# Update prev
if next_id:
prev_id = id (node)
node = self .__type_cast(next_id)
# Update curr
if next_id:
prev1_id = id (node1)
node1 = self .__type_cast(next1_id)
node1 = self .__type_cast(next1_id)
print (node1.value)
# Function to print elements of the XOR Linked List
def printList( self ):
if self .head ! = None :
prev_id = 0
node = self .head
next_id = 1
print (node.value, end = ' ' )
# Traverse XOR linked list
while next_id:
# Forward traversal
next_id = prev_id ^ node.npx
if next_id:
# Update prev
prev_id = id (node)
# Update curr
node = self .__type_cast(next_id)
# Print current node
print (node.value, end = ' ' )
else :
return
# method to check if the linked list is empty or not
def isEmpty( self ):
if self .head is None :
return True
return False
# method to return a new instance of type
def __type_cast( self , id ):
return ctypes.cast( id , ctypes.py_object).value
# Create following XOR Linked List # head -->7 –> 6 –>8 –> 11 –> 3 –> 1 –> 2 –> 0 head = XorLinkedList()
head.insert( 0 )
head.insert( 2 )
head.insert( 1 )
head.insert( 3 )
head.insert( 11 )
head.insert( 8 )
head.insert( 6 )
head.insert( 7 )
head.NthNode( 3 )
# This code is contributed by Nidhi goel. |
Output
1
Time Complexity: O(N)
Auxiliary Space: O(1)