• Last Updated : 03 Nov, 2022

Given an XOR linked list, the task is to delete the node at the end of the XOR Linked List.

Examples:

Input: 4<–>7<–>9<–>7
Output: 4<–>7<–>9
Explanation: Deleting a node from the end modifies the given XOR Linked List to 4<–>7<–>9

Input: 10
Output: List is empty
Explanation: After deleting the only node present in the XOR Linked List, the list becomes empty.

Approach: The idea to solve this problem is to traverse the XOR linked list until the last node is reached and update the address of its previous node. Follow the steps below to solve the problem:

• If the XOR linked list is empty, then print “List is empty“.
• Traverse the XOR Linked List until the last node of the Linked List is reached.
• Update the address of its previous node.
• Delete the last node from memory.
• If the list becomes empty after deleting the last node, then print “List is empty”. Otherwise, print the remaining nodes of the linked list.

Below is the implementation of the above approach:

C++

 `// C++ program for the above approach``#include ``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;``    ``}``}` `// Function to delete the last node present in the XOR Linked List``struct` `Node* delEnd(``struct` `Node** head)``{``    ``// Base condition``    ``if` `(*head == NULL)``        ``cout << ``"List is empty"``;``    ``else``    ``{``      ` `        ``// 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` `(XOR(curr->nxp, prev) != NULL)``        ``{``            ``// Forward traversal``            ``next = XOR(prev, curr->nxp);``          ` `            ``// Update prev``            ``prev = curr;``          ` `            ``// Update curr``            ``curr = next;``        ``}``        ``// If the Linked List contains more than 1 node``        ``if` `(prev != NULL) {``            ``prev->nxp = XOR(XOR(prev->nxp, curr), NULL);``        ``}``        ``// Otherwise``        ``else` `{``            ``*head = NULL;``        ``}` `        ``// Delete the last node from memory``        ``delete``(curr);``    ``}` `    ``// Returns head of new linked list``    ``return` `*head;``}` `// Driver Code``int` `main()``{` `    ``/* Create the XOR Linked List``    ``head-->40<-->30<-->20<-->10 */``    ``struct` `Node* head = NULL;``    ``insert(&head, 10);``    ``insert(&head, 20);``    ``insert(&head, 30);``    ``insert(&head, 40);` `    ``delEnd(&head);` `    ``// If the list had a single node``    ``if` `(head == NULL)``        ``cout << ``"List is empty"``;``    ``else``        ``// Print the list after deletion``        ``printList(&head);` `    ``return` `(0);``}` `// This code is contributed by ajaymakvana`

C

 `// C program for the above approach` `#include ``#include ``#include ` `// 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;``    ``}``}` `// Function to delete the last node``// present in the XOR Linked List``struct` `Node* delEnd(``struct` `Node** head)``{``    ``// Base condition``    ``if` `(*head == NULL)``        ``printf``(``"List is empty"``);``    ``else` `{` `        ``// 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` `(XOR(curr->nxp, prev) != NULL) {` `            ``// Forward traversal``            ``next = XOR(prev, curr->nxp);` `            ``// Update prev``            ``prev = curr;` `            ``// Update curr``            ``curr = next;``        ``}``        ``// If the Linked List contains more than 1 node``        ``if` `(prev != NULL)``            ``prev->nxp = XOR(XOR(prev->nxp, curr), NULL);` `        ``// Otherwise``        ``else``            ``*head = NULL;` `        ``// Delete the last node from memory``        ``free``(curr);``    ``}` `    ``// Returns head of new linked list``    ``return` `*head;``}` `// Driver Code``int` `main()``{` `    ``/* Create the XOR Linked List``    ``head-->40<-->30<-->20<-->10 */``    ``struct` `Node* head = NULL;``    ``insert(&head, 10);``    ``insert(&head, 20);``    ``insert(&head, 30);``    ``insert(&head, 40);` `    ``delEnd(&head);` `    ``// If the list had a single node``    ``if` `(head == NULL)``        ``printf``(``"List is empty"``);``    ``else``        ``// Print the list after deletion``        ``printList(&head);` `    ``return` `(0);``}`

Output:

`40 30 20`

Time Complexity: O(N)
Auxiliary Space: O(1)

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