add 2 py files and functions

Answers/40130212009/DoubleLinkedList.py

@@ -0,0 +1,195 @@
+class Node:
+    def __init__(self, value):
+        # Initialize a new node with the given value
+        self.value = value
+        self.next = None  # Pointer to the next node in the list
+        self.prev = None  # Pointer to the previous node in the list
+
+class DoublyLinkedList:
+    def __init__(self):
+        # Initialize an empty doubly linked list
+        self.head = None  # Pointer to the first node in the list
+        self.tail = None  # Pointer to the last node in the list
+
+    def insert_in_front(self, value):
+        # Insert a new node with the given value at the front of the list
+        new_node = Node(value)
+        new_node.next = self.head
+        if self.head:
+            self.head.prev = new_node
+        self.head = new_node
+        if not self.tail:
+            self.tail = new_node
+
+    def insert_in_back(self, value):
+        # Insert a new node with the given value at the back of the list
+        new_node = Node(value)
+        if not self.head:
+            self.head = new_node
+            self.tail = new_node
+            return
+        self.tail.next = new_node
+        new_node.prev = self.tail
+        self.tail = new_node
+
+    def search(self, value):
+        # Search for a node with the given value in the list
+        index = 0
+        current = self.head
+        while current:
+            if current.value == value:
+                return index  # Return the index of the node if found
+            index += 1
+            current = current.next
+        return 'Not Found!'  # Return 'Not Found!' if the value is not in the list
+
+    def delete_at_front(self):
+        # Delete the node at the front of the list and return its value
+        if not self.head:
+            return None
+        deleted_node = self.head.value
+        if self.head == self.tail:
+            self.head = self.tail = None
+        else:
+            self.head = self.head.next
+            self.head.prev = None
+        return deleted_node
+
+    def delete_at_back(self):
+        # Delete the node at the back of the list and return its value
+        if not self.head:
+            return None
+        if self.head == self.tail:
+            deleted_node = self.head.value
+            self.head = self.tail = None
+            return deleted_node
+        deleted_node = self.tail.value
+        self.tail = self.tail.prev
+        self.tail.next = None
+        return deleted_node
+
+    def size(self):
+        # Calculate and return the size (number of nodes) of the list
+        num = 0
+        current = self.head
+        while current:
+            num += 1
+            current = current.next
+        return num
+
+    def clear(self):
+        # Clear the list by setting head and tail to None
+        self.head = None
+        self.tail = None
+
+    def print_forward(self):
+        # Print the values of the list from head to tail
+        current = self.head
+        while current:
+            print(current.value, end=' ')
+            current = current.next
+        print('None')
+
+    def print_backward(self):
+        # Print the values of the list from tail to head
+        current = self.tail
+        while current:
+            print(current.value, end=' ')
+            current = current.prev
+        print('None')
+
+    def make_doubly(self, singly_list):
+        # Convert a singly linked list to a doubly linked list
+        doubly_list = DoublyLinkedList()
+        if not singly_list.head:
+            return 'The list is empty!'
+        current = singly_list.head
+        previous = None
+        while current:
+            current.prev = previous
+            previous = current
+            current = current.next
+
+    def reverse_non_recursive(self):
+        # Reverse the list in place non-recursively
+        if not self.head or not self.head.next:
+            return self.head
+
+        p = None
+        current = self.head
+        while current:
+            next_node = current.next
+            current.next = p
+            current.prev = next_node
+            p = current
+            current = next_node
+        self.head = p
+        return self.head
+
+# Example usage of DoublyLinkedList
+
+# Create a new doubly linked list
+dll = DoublyLinkedList()
+
+# Insert elements at the front of the list
+dll.insert_in_front(10)
+dll.insert_in_front(20)
+dll.insert_in_front(30)
+
+# Print the list forward
+print("List after inserting 30, 20, 10 at the front:")
+dll.print_forward()  # Output: 30 20 10 None
+
+# Insert elements at the back of the list
+dll.insert_in_back(40)
+dll.insert_in_back(50)
+
+# Print the list forward
+print("List after inserting 40, 50 at the back:")
+dll.print_forward()  # Output: 30 20 10 40 50 None
+
+# Print the list backward
+print("List printed backward:")
+dll.print_backward()  # Output: 50 40 10 20 30 None
+
+# Search for an element in the list
+print("Search for value 20:")
+print(dll.search(20))  # Output: 1
+
+print("Search for value 60:")
+print(dll.search(60))  # Output: Not Found!
+
+# Delete elements at the front and back of the list
+print("Delete at front:")
+print(dll.delete_at_front())  # Output: 30
+
+print("Delete at back:")
+print(dll.delete_at_back())  # Output: 50
+
+# Print the list forward after deletions
+print("List after deleting front and back:")
+dll.print_forward()  # Output: 20 10 40 None
+
+# Get the size of the list
+print("Size of the list:")
+print(dll.size())  # Output: 3
+
+# Clear the list
+dll.clear()
+print("List after clearing:")
+dll.print_forward()  # Output: None
+
+# Insert more elements to demonstrate reversing the list
+dll.insert_in_front(1)
+dll.insert_in_back(2)
+dll.insert_in_back(3)
+dll.insert_in_back(4)
+
+# Print the list before reversing
+print("List before reversing:")
+dll.print_forward()  # Output: 1 2 3 4 None
+
+# Reverse the list
+dll.reverse_non_recursive()
+print("List after reversing:")
+dll.print_forward()  # Output: 4 3 2 1 None

Answers/40130212009/SingleLinkedList.py

@@ -0,0 +1,119 @@
+class Node:
+    def __init__(self, value):
+        self.value = value
+        self.next = None  # Pointer to the next node in the list
+
+class LinkedList:
+    def __init__(self):
+        self.head = None  # Initialize an empty list with head as None
+
+    def insert_in_back(self, value):
+        """Insert a new node with the given value at the back of the list."""
+        new_node = Node(value)
+        if not self.head:  # If the list is empty
+            self.head = new_node
+            return
+        current = self.head
+        while current.next:  # Traverse to the end of the list
+            current = current.next
+        current.next = new_node  # Link the new node at the end
+
+    def insert_in_front(self, value):
+        """Insert a new node with the given value at the front of the list."""
+        new_node = Node(value)
+        new_node.next = self.head  # Link the new node to the current head
+        self.head = new_node  # Update the head to the new node
+
+    def delete_at_back(self):
+        """Delete the node at the back of the list and return its value."""
+        if not self.head:  # If the list is empty
+            return None
+        if not self.head.next:  # If there is only one node in the list
+            deleted_node = self.head.value
+            self.head = None  # List becomes empty
+            return deleted_node
+        current = self.head
+        while current.next.next:  # Traverse to the second last node
+            current = current.next
+        deleted_node = current.next.value
+        current.next = None  # Remove the last node
+        return deleted_node
+
+    def delete_at_front(self):
+        """Delete the node at the front of the list and return its value."""
+        if not self.head:  # If the list is empty
+            return None
+        deleted_node = self.head.value
+        self.head = self.head.next  # Update the head to the next node
+        return deleted_node
+
+    def search(self, value):
+        """Search for a node with the given value and return its index. Return 'Not Found!' if not present."""
+        index = 0
+        current = self.head
+        while current:
+            if current.value == value:  # If the value is found
+                return index
+            index += 1
+            current = current.next
+        return 'Not Found!'  # Value is not found
+
+    def clear(self):
+        """Clear the entire list."""
+        self.head = None  # Reset head to None
+
+    def size(self):
+        """Return the number of nodes in the list."""
+        num = 0
+        current = self.head
+        while current:
+            num += 1  # Increment count for each node
+            current = current.next
+        return num
+
+    def print_forward(self):
+        """Print the values in the list from front to back."""
+        current = self.head
+        while current:
+            print(current.value, end=' ')  # Print each value
+            current = current.next
+        print()  # For a new line after printing all values
+
+    def print_backward(self):
+        """Print the values in the list from back to front."""
+        stack = []
+        current = self.head
+        while current:
+            stack.append(current.value)  # Use a stack to reverse the order
+            current = current.next
+        while stack:
+            print(stack.pop(), end=' ')  # Print values from the stack
+        print()  # For a new line after printing all values
+
+    def reverse_non_recursive(self):
+        """Reverse the list non-recursively."""
+        prev = None
+        current = self.head
+        while current:
+            next_node = current.next  # Store the next node
+            current.next = prev  # Reverse the link
+            prev = current  # Move prev to current node
+            current = next_node  # Move to the next node
+        self.head = prev  # Update head to the new front
+
+# Example usage of LinkedList class
+my_list = LinkedList()
+my_list.insert_in_back(10)
+my_list.insert_in_back(20)
+my_list.insert_in_back(30)
+my_list.insert_in_front(5)
+my_list.print_forward()  # Output: 5 10 20 30
+my_list.delete_at_back()
+my_list.print_forward()  # Output: 5 10 20
+my_list.delete_at_front()
+my_list.print_forward()  # Output: 10 20
+print("Size of the list:", my_list.size())  # Output: Size of the list: 2
+print("Search for value 10:", my_list.search(10))  # Output: Search for value 10: 0
+print("Search for value 15:", my_list.search(15))  # Output: Search for value 15: Not Found!
+my_list.reverse_non_recursive()
+my_list.print_forward()  # Output: 20 10