Delete last occurrence of an item from linked list
Loop through the whole list and use a double pointer to keep track of the node containing the address of last occurrence node.
C++
#include <iostream>#include <bits/stdc++.h>using namespace std;// A linked list Nodestruct Node { int data; struct Node* next;};// Function to delete the last occurrencevoid deleteLast(struct Node** head, int x){ struct Node** tmp1 = NULL; while (*head) { if ((*head)->data == x) { tmp1 = head; } head = &(*head)->next; } if (tmp1) { struct Node* tmp = *tmp1; *tmp1 = tmp->next; free(tmp); }}// Utility function to create a new node with// given key struct Node* newNode(int x){ Node* node = new Node ; node->data = x; node->next = NULL; return node;}// This function prints contents of linked// list starting from the given Nodevoid display(struct Node* head){ struct Node* temp = head; if (head == NULL) { cout << "NULL\n"; return; } while (temp != NULL) { cout << temp->data <<" --> "; temp = temp->next; } cout << "NULL\n";}// Driver codeint main(){ struct Node* head = newNode(1); head->next = newNode(2); head->next->next = newNode(3); head->next->next->next = newNode(4); head->next->next->next->next = newNode(5); head->next->next->next->next->next = newNode(4); head->next->next->next->next->next->next = newNode(4); cout << "Created Linked list: "; display(head); // Pass the address of the head pointer deleteLast(&head, 4); cout << "List after deletion of 4: "; display(head); return 0;}// This code is contributed by khushboogoyal499 |
C
#include <stdio.h>#include <stdlib.h>// A linked list Nodestruct Node { int data; struct Node* next;};// Function to delete the last occurrencevoid deleteLast(struct Node** head, int x){ struct Node** tmp1 = NULL; while(*head) { if((*head)->data == x) { tmp1 = head; } head = &(*head)->next; } if(tmp1) { struct Node* tmp = *tmp1; *tmp1 = tmp->next; free(tmp); }}/* Utility function to create a new node withgiven key */struct Node* newNode(int x){ struct Node* node = malloc(sizeof(struct Node*)); node->data = x; node->next = NULL; return node;}// This function prints contents of linked list// starting from the given Nodevoid display(struct Node* head){ struct Node* temp = head; if (head == NULL) { printf("NULL\n"); return; } while (temp != NULL) { printf("%d --> ", temp->data); temp = temp->next; } printf("NULL\n");}/* Driver program to test above functions*/int main(){ struct Node* head = newNode(1); head->next = newNode(2); head->next->next = newNode(3); head->next->next->next = newNode(4); head->next->next->next->next = newNode(5); head->next->next->next->next->next = newNode(4); head->next->next->next->next->next->next = newNode(4); printf("Created Linked list: "); display(head); deleteLast(&head, 4); // Pass the address of the head pointer printf("List after deletion of 4: "); display(head); return 0;} |
Python3
# A linked list Nodeclass Node: def __init__(self, new_data): self.data = new_data self.next = None# Function to delete the last occurrencedef deleteLast(head, x): temp = head ptr = None while (temp != None): # If found key, update if (temp.data == x): ptr = temp temp = temp.next # If the last occurrence is the last node if (ptr != None and ptr.next == None): temp = head while (temp.next != ptr): temp = temp.next temp.next = None # If it is not the last node if (ptr != None and ptr.next != None): ptr.data = ptr.next.data temp = ptr.next ptr.next = ptr.next.next return head # Utility function to create a new node# with given key def newNode(x): node = Node(0) node.data = x node.next = None return node# This function prints contents of linked # list starting from the given Nodedef display(head): temp = head if (head == None): print("NULL\n") return while (temp != None): print( temp.data," --> ", end = "") temp = temp.next print("NULL")# Driver codehead = newNode(1)head.next = newNode(2)head.next.next = newNode(3)head.next.next.next = newNode(4)head.next.next.next.next = newNode(5)head.next.next.next.next.next = newNode(4)head.next.next.next.next.next.next = newNode(4)print("Created Linked list: ", end = '')display(head)# Pass the address of the head pointerhead = deleteLast(head, 4) print("List after deletion of 4: ", end = '')display(head)# This code is contributed by rutvik_56 |
Output
Created Linked list: 1 --> 2 --> 3 --> 4 --> 5 --> 4 --> 4 --> NULL List after deletion of 4: 1 --> 2 --> 3 --> 4 --> 5 --> 4 --> NULL
Given a liked list and a key to be deleted. Delete last occurrence of key from linked. The list may have duplicates.
Examples:
Input: 1->2->3->5->2->10, key = 2 Output: 1->2->3->5->10
The idea is to traverse the linked list from beginning to end. While traversing, keep track of last occurrence key. After traversing the complete list, delete last occurrence by copying data of next node and deleting the next node.
C++
// A C++ program to demonstrate deletion of last// Node in singly linked list#include <bits/stdc++.h>// A linked list Nodestruct Node { int key; struct Node* next;};void deleteLast(Node* head, int key){ // Initialize previous of Node to be deleted Node* x = NULL; // Start from head and find the Node to be // deleted Node* temp = head; while (temp) { // If we found the key, update xv if (temp->key == key) x = temp; temp = temp->next; } // key occurs at-least once if (x != NULL) { // Copy key of next Node to x x->key = x->next->key; // Store and unlink next temp = x->next; x->next = x->next->next; // Free memory for next delete temp; }}/* Utility function to create a new node with given key */Node* newNode(int key){ Node* temp = new Node; temp->key = key; temp->next = NULL; return temp;}// This function prints contents of linked list// starting from the given Nodevoid printList(struct Node* node){ while (node != NULL) { printf(" %d ", node->key); node = node->next; }}/* Driver program to test above functions*/int main(){ /* Start with the empty list */ struct Node* head = newNode(1); head->next = newNode(2); head->next->next = newNode(3); head->next->next->next = newNode(5); head->next->next->next->next = newNode(2); head->next->next->next->next->next = newNode(10); puts("Created Linked List: "); printList(head); deleteLast(head, 2); puts("\nLinked List after Deletion of 1: "); printList(head); return 0;} |
Java
// A Java program to demonstrate deletion of last // Node in singly linked list class GFG{ // A linked list Node static class Node { int key; Node next; }; static Node deleteLast(Node head, int key) { // Initialize previous of Node to be deleted Node x = null; // Start from head and find the Node to be // deleted Node temp = head; while (temp != null) { // If we found the key, update xv if (temp.key == key) x = temp; temp = temp.next; } // key occurs at-least once if (x != null) { // Copy key of next Node to x x.key = x.next.key; // Store and unlink next temp = x.next; x.next = x.next.next; // Free memory for next } return head;} /// Utility function to create a new node with //given key /static Node newNode(int key) { Node temp = new Node(); temp.key = key; temp.next = null; return temp; } // This function prints contents of linked list // starting from the given Node static void printList( Node node) { while (node != null) { System.out.printf(" %d ", node.key); node = node.next; } } // Driver code/public static void main(String args[]){ // /Start with the empty list / Node head = newNode(1); head.next = newNode(2); head.next.next = newNode(3); head.next.next.next = newNode(5); head.next.next.next.next = newNode(2); head.next.next.next.next.next = newNode(10); System.out.printf("Created Linked List: "); printList(head); deleteLast(head, 2); System.out.printf("\nLinked List after Deletion of 1: "); printList(head); }} // This code is contributed by Arnab Kundu |
Python3
# Python3 program to demonstrate deletion of # last Node in singly linked list # A linked list Node class Node: # Constructor to initialize the node object def __init__(self, data): self.data = data self.next = Nonedef deleteLast(head, key) : # Initialize previous of Node to be deleted x = None # Start from head and find the Node to be # deleted temp = head while (temp != None) : # If we found the key, update xv if (temp.key == key) : x = temp temp = temp.next # key occurs at-least once if (x != None) : # Copy key of next Node to x x.key = x.next.key # Store and unlink next temp = x.next x.next = x.next.next # Free memory for next return head# Utility function to create # a new node with given key def newNode(key) : temp = Node(0) temp.key = key temp.next = None return temp # This function prints contents of linked list # starting from the given Node def printList( node) : while (node != None) : print ( node.key, end = " ") node = node.next # Driver Code if __name__=='__main__': # Start with the empty list head = newNode(1) head.next = newNode(2) head.next.next = newNode(3) head.next.next.next = newNode(5) head.next.next.next.next = newNode(2) head.next.next.next.next.next = newNode(10) print("Created Linked List: ") printList(head) deleteLast(head, 2) print("\nLinked List after Deletion of 1: ") printList(head) # This code is contributed by Arnab Kundu |
C#
// C# program to demonstrate deletion of last // Node in singly linked list using System;class GFG { // A linked list Node public class Node { public int key; public Node next; }; static Node deleteLast(Node head, int key) { // Initialize previous of Node to be deleted Node x = null; // Start from head and find the Node to be // deleted Node temp = head; while (temp != null) { // If we found the key, update xv if (temp.key == key) x = temp; temp = temp.next; } // key occurs at-least once if (x != null) { // Copy key of next Node to x x.key = x.next.key; // Store and unlink next temp = x.next; x.next = x.next.next; // Free memory for next } return head; } /// Utility function to create a new node with //given key / static Node newNode(int key) { Node temp = new Node(); temp.key = key; temp.next = null; return temp; } // This function prints contents of linked list // starting from the given Node static void printList( Node node) { while (node != null) { Console.Write(" {0} ", node.key); node = node.next; } } // Driver codepublic static void Main(String []args) { // Start with the empty list Node head = newNode(1); head.next = newNode(2); head.next.next = newNode(3); head.next.next.next = newNode(5); head.next.next.next.next = newNode(2); head.next.next.next.next.next = newNode(10); Console.Write("Created Linked List: "); printList(head); deleteLast(head, 2); Console.Write("\nLinked List after Deletion of 1: "); printList(head); } } // This code has been contributed by 29AjayKumar |
Output:
Created Linked List: 1 2 3 5 2 10 Linked List after Deletion of 1: 1 2 3 5 10
The above solution doesn’t work when the node to be deleted is the last node.
Following solution handles all cases.
C
// A C program to demonstrate deletion of last// Node in singly linked list#include <stdio.h>#include <stdlib.h>// A linked list Nodestruct Node { int data; struct Node* next;};// Function to delete the last occurrencevoid deleteLast(struct Node* head, int x){ struct Node *temp = head, *ptr = NULL; while (temp) { // If found key, update if (temp->data == x) ptr = temp; temp = temp->next; } // If the last occurrence is the last node if (ptr != NULL && ptr->next == NULL) { temp = head; while (temp->next != ptr) temp = temp->next; temp->next = NULL; } // If it is not the last node if (ptr != NULL && ptr->next != NULL) { ptr->data = ptr->next->data; temp = ptr->next; ptr->next = ptr->next->next; free(temp); }}/* Utility function to create a new node withgiven key */struct Node* newNode(int x){ struct Node* node = malloc(sizeof(struct Node*)); node->data = x; node->next = NULL; return node;}// This function prints contents of linked list// starting from the given Nodevoid display(struct Node* head){ struct Node* temp = head; if (head == NULL) { printf("NULL\n"); return; } while (temp != NULL) { printf("%d --> ", temp->data); temp = temp->next; } printf("NULL\n");}/* Driver program to test above functions*/int main(){ struct Node* head = newNode(1); head->next = newNode(2); head->next->next = newNode(3); head->next->next->next = newNode(4); head->next->next->next->next = newNode(5); head->next->next->next->next->next = newNode(4); head->next->next->next->next->next->next = newNode(4); printf("Created Linked list: "); display(head); deleteLast(head, 4); printf("List after deletion of 4: "); display(head); return 0;} |
Java
// Java program to demonstrate deletion of last // Node in singly linked list class GFG {// A linked list Node static class Node { int data; Node next; }; // Function to delete the last occurrence static void deleteLast(Node head, int x) { Node temp = head, ptr = null; while (temp!=null) { // If found key, update if (temp.data == x) ptr = temp; temp = temp.next; } // If the last occurrence is the last node if (ptr != null && ptr.next == null) { temp = head; while (temp.next != ptr) temp = temp.next; temp.next = null; } // If it is not the last node if (ptr != null && ptr.next != null) { ptr.data = ptr.next.data; temp = ptr.next; ptr.next = ptr.next.next; System.gc(); } } /* Utility function to create a new node with given key */static Node newNode(int x) { Node node = new Node(); node.data = x; node.next = null; return node; } // This function prints contents of linked list // starting from the given Node static void display(Node head) { Node temp = head; if (head == null) { System.out.print("null\n"); return; } while (temp != null) { System.out.printf("%d --> ", temp.data); temp = temp.next; } System.out.print("null\n"); } /* Driver code*/public static void main(String[] args) { Node head = newNode(1); head.next = newNode(2); head.next.next = newNode(3); head.next.next.next = newNode(4); head.next.next.next.next = newNode(5); head.next.next.next.next.next = newNode(4); head.next.next.next.next.next.next = newNode(4); System.out.print("Created Linked list: "); display(head); deleteLast(head, 4); System.out.print("List after deletion of 4: "); display(head); }}/* This code is contributed by PrinciRaj1992 */ |
Python3
# A Python3 program to demonstrate deletion of last# Node in singly linked list# A linked list Nodeclass Node: def __init__(self, new_data): self.data = new_data self.next = None# Function to delete the last occurrencedef deleteLast(head, x): temp = head ptr = None while (temp!=None): # If found key, update if (temp.data == x) : ptr = temp temp = temp.next # If the last occurrence is the last node if (ptr != None and ptr.next == None): temp = head while (temp.next != ptr) : temp = temp.next temp.next = None # If it is not the last node if (ptr != None and ptr.next != None): ptr.data = ptr.next.data temp = ptr.next ptr.next = ptr.next.next return head # Utility function to create a new node with# given key def newNode(x): node = Node(0) node.data = x node.next = None return node# This function prints contents of linked list# starting from the given Nodedef display( head): temp = head if (head == None): print("None\n") return while (temp != None): print( temp.data," -> ",end="") temp = temp.next print("None")# Driver codehead = newNode(1)head.next = newNode(2)head.next.next = newNode(3)head.next.next.next = newNode(4)head.next.next.next.next = newNode(5)head.next.next.next.next.next = newNode(4)head.next.next.next.next.next.next = newNode(4)print("Created Linked list: ")display(head)head = deleteLast(head, 4)print("List after deletion of 4: ")display(head)# This code is contributed by Arnab Kundu |
C#
// C# program to demonstrate deletion of last // Node in singly linked list using System;class GFG {// A linked list Node public class Node { public int data; public Node next; }; // Function to delete the last occurrence static void deleteLast(Node head, int x) { Node temp = head, ptr = null; while (temp != null) { // If found key, update if (temp.data == x) ptr = temp; temp = temp.next; } // If the last occurrence is the last node if (ptr != null && ptr.next == null) { temp = head; while (temp.next != ptr) temp = temp.next; temp.next = null; } // If it is not the last node if (ptr != null && ptr.next != null) { ptr.data = ptr.next.data; temp = ptr.next; ptr.next = ptr.next.next; } } /* Utility function to create a new node with given key */static Node newNode(int x) { Node node = new Node(); node.data = x; node.next = null; return node; } // This function prints contents of linked list // starting from the given Node static void display(Node head) { Node temp = head; if (head == null) { Console.Write("null\n"); return; } while (temp != null) { Console.Write("{0} --> ", temp.data); temp = temp.next; } Console.Write("null\n"); } /* Driver code*/public static void Main(String[] args) { Node head = newNode(1); head.next = newNode(2); head.next.next = newNode(3); head.next.next.next = newNode(4); head.next.next.next.next = newNode(5); head.next.next.next.next.next = newNode(4); head.next.next.next.next.next.next = newNode(4); Console.Write("Created Linked list: "); display(head); deleteLast(head, 4); Console.Write("List after deletion of 4: "); display(head); }}// This code contributed by Rajput-Ji |
Output:
Created Linked List: 1 2 3 4 5 4 4 Linked List after Deletion of 1: 1 2 3 4 5 4
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