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question:Write a code that inserts a new node at the end of a singly linked list. The linked list node contains an integer data field and a reference to the next node in the sequence. This node is defined by the Node class. Here is a Node class and the beginning of the LinkedList class ```python class Node: def __init__(self, data=None): self.data = data self.next = None class LinkedList: def __init__(self): self.head = None # Rest of your code here ``` Implement a method called insert_at_end() to add a new node at the end of the linked list with the specified data. If the list is empty (i.e., it has no head node), create a new head node containing the data. Otherwise, traverse the list to find the last node and append a new node to it. Your method should be able to handle cases where the linked list is empty or has one or more existing nodes. Here's an example usage of the insert_at_end() method: ```python # Create a LinkedList and add some nodes linked_list = LinkedList() linked_list.insert_at_end(10) linked_list.insert_at_end(20) linked_list.insert_at_end(30) # Print the data in all nodes node = linked_list.head while node: print(node.data, end= ) node = node.next ``` Output should be: 10 20 30
answer:To implement the `insert_at_end()` method in the `LinkedList` class, you can use the following code: ```python class Node: def __init__(self, data=None): self.data = data self.next = None class LinkedList: def __init__(self): self.head = None def insert_at_end(self, data): new_node = Node(data) # If the list is empty, set the new node as the head if self.head is None: self.head = new_node else: # Traverse the list to find the last node and append the new node to it current_node = self.head while current_node.next: current_node = current_node.next current_node.next = new_node # Create a LinkedList and add some nodes linked_list = LinkedList() linked_list.insert_at_end(10) linked_list.insert_at_end(20) linked_list.insert_at_end(30) # Print the data in all nodes node = linked_list.head while node: print(node.data, end= ) node = node.next ``` This code creates a new `Node` with the specified data and adds it to the end of the linked list. If the list is empty, the new node becomes the head of the list. Otherwise, it traverses the list to find the last node and appends the new node to it. The example usage at the end demonstrates how to create a `LinkedList`, add nodes to it using the `insert_at_end()` method, and print the data in all nodes.
question:Write a code that deletes a node with a given data from a singly linked list. The linked list node contains an integer data field and a reference to the next node in the sequence. Here is a Node class and the beginning of the LinkedList class ```python class Node: def __init__(self, data=None): self.data = data self.next = None class LinkedList: def __init__(self): self.head = None # Rest of your code here ``` Implement a method called delete_node() to remove the node with the specified data from the linked list. If the node to be deleted is the head node, update the head of the list. Otherwise, find the node before the one to be deleted and update its next pointer to skip the node to be deleted. Your method should be able to handle cases where the linked list is empty, the node to be deleted is the head node, the node to be deleted is in the middle or at the end of the list, or the node to be deleted does not exist in the list. Here's an example usage of the delete_node() method: ```python # Create a LinkedList and add some nodes linked_list = LinkedList() linked_list.insert_at_end(10) linked_list.insert_at_end(20) linked_list.insert_at_end(30) # Delete a node linked_list.delete_node(20) # Print the data in all nodes node = linked_list.head while node: print(node.data, end= ) node = node.next ``` Output should be: 10 30 You will also need to add the insert_at_end method to the LinkedList class like in the previous task. ```python def insert_at_end(self, data): new_node = Node(data) # If the list is empty, set the new node as the head if self.head is None: self.head = new_node else: # Traverse the list to find the last node and append the new node to it current_node = self.head while current_node.next: current_node = current_node.next current_node.next = new_node ```
answer:To implement the `delete_node()` method in the `LinkedList` class, you can use the following code: ```python class Node: def __init__(self, data=None): self.data = data self.next = None class LinkedList: def __init__(self): self.head = None def insert_at_end(self, data): new_node = Node(data) # If the list is empty, set the new node as the head if self.head is None: self.head = new_node else: # Traverse the list to find the last node and append the new node to it current_node = self.head while current_node.next: current_node = current_node.next current_node.next = new_node def delete_node(self, data): # If the list is empty, return immediately if self.head is None: return # If the node to be deleted is the head node, update the head of the list if self.head.data == data: self.head = self.head.next return # Traverse the list to find the node before the one to be deleted current_node = self.head while current_node.next and current_node.next.data != data: current_node = current_node.next # If the node to be deleted is found, update the next pointer of the previous node if current_node.next: current_node.next = current_node.next.next # Create a LinkedList and add some nodes linked_list = LinkedList() linked_list.insert_at_end(10) linked_list.insert_at_end(20) linked_list.insert_at_end(30) # Delete a node linked_list.delete_node(20) # Print the data in all nodes node = linked_list.head while node: print(node.data, end= ) node = node.next ``` This code defines the `delete_node()` method, which removes the node with the specified data from the linked list. It handles various cases such as when the list is empty, the node to be deleted is the head node, the node to be deleted is in the middle or at the end of the list, or the node to be deleted does not exist in the list. The `insert_at_end()` method is also included for adding nodes to the linked list. The example usage demonstrates how to create a `LinkedList`, add nodes, delete a node, and print the data in all nodes.
question:Write a code that reverses a singly linked list. The linked list node contains an integer data field and a reference to the next node in the sequence. Here is a Node class and the beginning of the LinkedList class ```python class Node: def __init__(self, data=None): self.data = data self.next = None class LinkedList: def __init__(self): self.head = None # Rest of your code here ``` Implement a method called reverse() to reverse the order of the nodes in the linked list. You can do this by iteratively reversing the next pointers of the nodes. Your method should be able to handle cases where the linked list is empty or has one or more nodes. Here's an example usage of the reverse() method: ```python # Create a LinkedList and add some nodes linked_list = LinkedList() linked_list.insert_at_end(10) linked_list.insert_at_end(20) linked_list.insert_at_end(30) # Reverse the linked list linked_list.reverse() # Print the data in all nodes node = linked_list.head while node: print(node.data, end= ) node = node.next ``` Output should be: 30 20 10 You will also need to add the insert_at_end method to the LinkedList class like in the previous task. ```python def insert_at_end(self, data): new_node = Node(data) # If the list is empty, set the new node as the head if self.head is None: self.head = new_node else: # Traverse the list to find the last node and append the new node to it current_node = self.head while current_node.next: current_node = current_node.next current_node.next = new_node ```
answer:To implement the `reverse()` method in the `LinkedList` class, you can use the following code: ```python class Node: def __init__(self, data=None): self.data = data self.next = None class LinkedList: def __init__(self): self.head = None def insert_at_end(self, data): new_node = Node(data) # If the list is empty, set the new node as the head if self.head is None: self.head = new_node else: # Traverse the list to find the last node and append the new node to it current_node = self.head while current_node.next: current_node = current_node.next current_node.next = new_node def reverse(self): # If the list is empty or has only one node, return immediately if self.head is None or self.head.next is None: return # Initialize three pointers: previous, current, and next previous_node = None current_node = self.head next_node = None # Reverse the linked list while current_node: next_node = current_node.next # Store the next node current_node.next = previous_node # Reverse the link previous_node = current_node # Move the previous and current pointers current_node = next_node # Update the head of the reversed linked list self.head = previous_node # Create a LinkedList and add some nodes linked_list = LinkedList() linked_list.insert_at_end(10) linked_list.insert_at_end(20) linked_list.insert_at_end(30) # Reverse the linked list linked_list.reverse() # Print the data in all nodes node = linked_list.head while node: print(node.data, end= ) node = node.next ``` This code defines the `reverse()` method, which reverses the order of the nodes in the linked list. It uses three pointers (previous, current, and next) to iteratively reverse the next pointers of the nodes. The `insert_at_end()` method is also included for adding nodes to the linked list. The example usage demonstrates how to create a `LinkedList`, add nodes, reverse the linked list, and print the data in all nodes.
question:Use punctuation to improve sentence structure and flow: Sarah went to the store she forgot her wallet.
answer:Sarah went to the store, but she forgot her wallet.