[NEW ALGORITHM] Rotate linked list by K.

data_structures/linked_list/rotate_to_the_right.py

@@ -0,0 +1,156 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Node:
+ data: int
+ next_node: Node | None = None
+
+
+def print_linked_list(head: Node | None) -> None:
+ """
+ Print the entire linked list iteratively.
+
+ This function prints the elements of a linked list separated by '->'.
+
+ Parameters:
+ head (Node | None): The head of the linked list to be printed,
+ or None if the linked list is empty.
+
+ >>> head = insert_node(None, 0)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 1)
+ >>> print_linked_list(head)
+ 0->2->1
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> print_linked_list(head)
+ 0->2->1->4->5
+ """
+ if head is None:
+ return
+ while head.next_node is not None:
+ print(head.data, end="->")
+ head = head.next_node
+ print(head.data)
+
+
+def insert_node(head: Node | None, data: int) -> Node:
+ """
+ Insert a new node at the end of a linked list and return the new head.
+
+ Parameters:
+ head (Node | None): The head of the linked list.
+ data (int): The data to be inserted into the new node.
+
+ Returns:
+ Node: The new head of the linked list.
+
+ >>> head = insert_node(None, 10)
+ >>> head = insert_node(head, 9)
+ >>> head = insert_node(head, 8)
+ >>> print_linked_list(head)
+ 10->9->8
+ """
+ new_node = Node(data)
+ # If the linked list is empty, the new_node becomes the head
+ if head is None:
+ return new_node
+
+ temp_node = head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+
+ temp_node.next_node = new_node # type: ignore
+ return head
+
+
+def rotate_to_the_right(head: Node, places: int) -> Node:
+ """
+ Rotate a linked list to the right by places times.
+
+ Parameters:
+ head: The head of the linked list.
+ places: The number of places to rotate.
+
+ Returns:
+ Node: The head of the rotated linked list.
+
+ >>> rotate_to_the_right(None, places=1)
+ Traceback (most recent call last):
+ ...
+ ValueError: The linked list is empty.
+ >>> head = insert_node(None, 1)
+ >>> rotate_to_the_right(head, places=1) == head
+ True
+ >>> head = insert_node(None, 1)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 3)
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> new_head = rotate_to_the_right(head, places=2)
+ >>> print_linked_list(new_head)
+ 4->5->1->2->3
+ """
+ # Check if the list is empty or has only one element
+ if not head:
+ raise ValueError("The linked list is empty.")
+
+ if head.next_node is None:
+ return head
+
+ # Calculate the length of the linked list
+ length = 1
+ temp_node = head
+ while temp_node.next_node is not None:
+ length += 1
+ temp_node = temp_node.next_node
+
+ # Adjust the value of places to avoid places longer than the list.
+ places %= length
+
+ if places == 0:
+ return head # As no rotation is needed.
+
+ # Find the new head position after rotation.
+ new_head_index = length - places
+
+ # Traverse to the new head position
+ temp_node = head
+ for _ in range(new_head_index - 1):
+ assert temp_node.next_node
+ temp_node = temp_node.next_node
+
+ # Update pointers to perform rotation
+ assert temp_node.next_node
+ new_head = temp_node.next_node
+ temp_node.next_node = None
+ temp_node = new_head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+ temp_node.next_node = head
+
+ assert new_head
+ return new_head
+
+
+if __name__ == "__main__":
+ import doctest
+
+ doctest.testmod()
+ head = insert_node(None, 5)
+ head = insert_node(head, 1)
+ head = insert_node(head, 2)
+ head = insert_node(head, 4)
+ head = insert_node(head, 3)
+
+ print("Original list: ", end="")
+ print_linked_list(head)
+
+ places = 3
+ new_head = rotate_to_the_right(head, places)
+
+ print(f"After {places} iterations: ", end="")
+ print_linked_list(new_head)

data_structures/linked_list/rotate_to_the_right.py

@@ -0,0 +1,156 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Node:
+ data: int
+ next_node: Node | None = None
+
+
+def print_linked_list(head: Node | None) -> None:
+ """
+ Print the entire linked list iteratively.
+
+ This function prints the elements of a linked list separated by '->'.
+
+ Parameters:
+ head (Node | None): The head of the linked list to be printed,
+ or None if the linked list is empty.
+
+ >>> head = insert_node(None, 0)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 1)
+ >>> print_linked_list(head)
+ 0->2->1
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> print_linked_list(head)
+ 0->2->1->4->5
+ """
+ if head is None:
+ return
+ while head.next_node is not None:
+ print(head.data, end="->")
+ head = head.next_node
+ print(head.data)
+
+
+def insert_node(head: Node | None, data: int) -> Node:
+ """
+ Insert a new node at the end of a linked list and return the new head.
+
+ Parameters:
+ head (Node | None): The head of the linked list.
+ data (int): The data to be inserted into the new node.
+
+ Returns:
+ Node: The new head of the linked list.
+
+ >>> head = insert_node(None, 10)
+ >>> head = insert_node(head, 9)
+ >>> head = insert_node(head, 8)
+ >>> print_linked_list(head)
+ 10->9->8
+ """
+ new_node = Node(data)
+ # If the linked list is empty, the new_node becomes the head
+ if head is None:
+ return new_node
+
+ temp_node = head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+
+ temp_node.next_node = new_node # type: ignore
+ return head
+
+
+def rotate_to_the_right(head: Node, places: int) -> Node:
+ """
+ Rotate a linked list to the right by places times.
+
+ Parameters:
+ head: The head of the linked list.
+ places: The number of places to rotate.
+
+ Returns:
+ Node: The head of the rotated linked list.
+
+ >>> rotate_to_the_right(None, places=1)
+ Traceback (most recent call last):
+ ...
+ ValueError: The linked list is empty.
+ >>> head = insert_node(None, 1)
+ >>> rotate_to_the_right(head, places=1) == head
+ True
+ >>> head = insert_node(None, 1)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 3)
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> new_head = rotate_to_the_right(head, places=2)
+ >>> print_linked_list(new_head)
+ 4->5->1->2->3
+ """
+ # Check if the list is empty or has only one element
+ if not head:
+ raise ValueError("The linked list is empty.")
+
+ if head.next_node is None:
+ return head
+
+ # Calculate the length of the linked list
+ length = 1
+ temp_node = head
+ while temp_node.next_node is not None:
+ length += 1
+ temp_node = temp_node.next_node
+
+ # Adjust the value of places to avoid places longer than the list.
+ places %= length
+
+ if places == 0:
+ return head # As no rotation is needed.
+
+ # Find the new head position after rotation.
+ new_head_index = length - places
+
+ # Traverse to the new head position
+ temp_node = head
+ for _ in range(new_head_index - 1):
+ assert temp_node.next_node
+ temp_node = temp_node.next_node
+
+ # Update pointers to perform rotation
+ assert temp_node.next_node
+ new_head = temp_node.next_node
+ temp_node.next_node = None
+ temp_node = new_head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+ temp_node.next_node = head
+
+ assert new_head
+ return new_head
+
+
+if __name__ == "__main__":
+ import doctest
+
+ doctest.testmod()
+ head = insert_node(None, 5)
+ head = insert_node(head, 1)
+ head = insert_node(head, 2)
+ head = insert_node(head, 4)
+ head = insert_node(head, 3)
+
+ print("Original list: ", end="")
+ print_linked_list(head)
+
+ places = 3
+ new_head = rotate_to_the_right(head, places)
+
+ print(f"After {places} iterations: ", end="")
+ print_linked_list(new_head)

data_structures/linked_list/rotate_to_the_right.py

@@ -0,0 +1,156 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Node:
+ data: int
+ next_node: Node | None = None
+
+
+def print_linked_list(head: Node | None) -> None:
+ """
+ Print the entire linked list iteratively.
+
+ This function prints the elements of a linked list separated by '->'.
+
+ Parameters:
+ head (Node | None): The head of the linked list to be printed,
+ or None if the linked list is empty.
+
+ >>> head = insert_node(None, 0)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 1)
+ >>> print_linked_list(head)
+ 0->2->1
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> print_linked_list(head)
+ 0->2->1->4->5
+ """
+ if head is None:
+ return
+ while head.next_node is not None:
+ print(head.data, end="->")
+ head = head.next_node
+ print(head.data)
+
+
+def insert_node(head: Node | None, data: int) -> Node:
+ """
+ Insert a new node at the end of a linked list and return the new head.
+
+ Parameters:
+ head (Node | None): The head of the linked list.
+ data (int): The data to be inserted into the new node.
+
+ Returns:
+ Node: The new head of the linked list.
+
+ >>> head = insert_node(None, 10)
+ >>> head = insert_node(head, 9)
+ >>> head = insert_node(head, 8)
+ >>> print_linked_list(head)
+ 10->9->8
+ """
+ new_node = Node(data)
+ # If the linked list is empty, the new_node becomes the head
+ if head is None:
+ return new_node
+
+ temp_node = head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+
+ temp_node.next_node = new_node # type: ignore
+ return head
+
+
+def rotate_to_the_right(head: Node, places: int) -> Node:
+ """
+ Rotate a linked list to the right by places times.
+
+ Parameters:
+ head: The head of the linked list.
+ places: The number of places to rotate.
+
+ Returns:
+ Node: The head of the rotated linked list.
+
+ >>> rotate_to_the_right(None, places=1)
+ Traceback (most recent call last):
+ ...
+ ValueError: The linked list is empty.
+ >>> head = insert_node(None, 1)
+ >>> rotate_to_the_right(head, places=1) == head
+ True
+ >>> head = insert_node(None, 1)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 3)
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> new_head = rotate_to_the_right(head, places=2)
+ >>> print_linked_list(new_head)
+ 4->5->1->2->3
+ """
+ # Check if the list is empty or has only one element
+ if not head:
+ raise ValueError("The linked list is empty.")
+
+ if head.next_node is None:
+ return head
+
+ # Calculate the length of the linked list
+ length = 1
+ temp_node = head
+ while temp_node.next_node is not None:
+ length += 1
+ temp_node = temp_node.next_node
+
+ # Adjust the value of places to avoid places longer than the list.
+ places %= length
+
+ if places == 0:
+ return head # As no rotation is needed.
+
+ # Find the new head position after rotation.
+ new_head_index = length - places
+
+ # Traverse to the new head position
+ temp_node = head
+ for _ in range(new_head_index - 1):
+ assert temp_node.next_node
+ temp_node = temp_node.next_node
+
+ # Update pointers to perform rotation
+ assert temp_node.next_node
+ new_head = temp_node.next_node
+ temp_node.next_node = None
+ temp_node = new_head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+ temp_node.next_node = head
+
+ assert new_head
+ return new_head
+
+
+if __name__ == "__main__":
+ import doctest
+
+ doctest.testmod()
+ head = insert_node(None, 5)
+ head = insert_node(head, 1)
+ head = insert_node(head, 2)
+ head = insert_node(head, 4)
+ head = insert_node(head, 3)
+
+ print("Original list: ", end="")
+ print_linked_list(head)
+
+ places = 3
+ new_head = rotate_to_the_right(head, places)
+
+ print(f"After {places} iterations: ", end="")
+ print_linked_list(new_head)

data_structures/linked_list/rotate_to_the_right.py

@@ -0,0 +1,156 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Node:
+ data: int
+ next_node: Node | None = None
+
+
+def print_linked_list(head: Node | None) -> None:
+ """
+ Print the entire linked list iteratively.
+
+ This function prints the elements of a linked list separated by '->'.
+
+ Parameters:
+ head (Node | None): The head of the linked list to be printed,
+ or None if the linked list is empty.
+
+ >>> head = insert_node(None, 0)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 1)
+ >>> print_linked_list(head)
+ 0->2->1
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> print_linked_list(head)
+ 0->2->1->4->5
+ """
+ if head is None:
+ return
+ while head.next_node is not None:
+ print(head.data, end="->")
+ head = head.next_node
+ print(head.data)
+
+
+def insert_node(head: Node | None, data: int) -> Node:
+ """
+ Insert a new node at the end of a linked list and return the new head.
+
+ Parameters:
+ head (Node | None): The head of the linked list.
+ data (int): The data to be inserted into the new node.
+
+ Returns:
+ Node: The new head of the linked list.
+
+ >>> head = insert_node(None, 10)
+ >>> head = insert_node(head, 9)
+ >>> head = insert_node(head, 8)
+ >>> print_linked_list(head)
+ 10->9->8
+ """
+ new_node = Node(data)
+ # If the linked list is empty, the new_node becomes the head
+ if head is None:
+ return new_node
+
+ temp_node = head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+
+ temp_node.next_node = new_node # type: ignore
+ return head
+
+
+def rotate_to_the_right(head: Node, places: int) -> Node:
+ """
+ Rotate a linked list to the right by places times.
+
+ Parameters:
+ head: The head of the linked list.
+ places: The number of places to rotate.
+
+ Returns:
+ Node: The head of the rotated linked list.
+
+ >>> rotate_to_the_right(None, places=1)
+ Traceback (most recent call last):
+ ...
+ ValueError: The linked list is empty.
+ >>> head = insert_node(None, 1)
+ >>> rotate_to_the_right(head, places=1) == head
+ True
+ >>> head = insert_node(None, 1)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 3)
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> new_head = rotate_to_the_right(head, places=2)
+ >>> print_linked_list(new_head)
+ 4->5->1->2->3
+ """
+ # Check if the list is empty or has only one element
+ if not head:
+ raise ValueError("The linked list is empty.")
+
+ if head.next_node is None:
+ return head
+
+ # Calculate the length of the linked list
+ length = 1
+ temp_node = head
+ while temp_node.next_node is not None:
+ length += 1
+ temp_node = temp_node.next_node
+
+ # Adjust the value of places to avoid places longer than the list.
+ places %= length
+
+ if places == 0:
+ return head # As no rotation is needed.
+
+ # Find the new head position after rotation.
+ new_head_index = length - places
+
+ # Traverse to the new head position
+ temp_node = head
+ for _ in range(new_head_index - 1):
+ assert temp_node.next_node
+ temp_node = temp_node.next_node
+
+ # Update pointers to perform rotation
+ assert temp_node.next_node
+ new_head = temp_node.next_node
+ temp_node.next_node = None
+ temp_node = new_head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+ temp_node.next_node = head
+
+ assert new_head
+ return new_head
+
+
+if __name__ == "__main__":
+ import doctest
+
+ doctest.testmod()
+ head = insert_node(None, 5)
+ head = insert_node(head, 1)
+ head = insert_node(head, 2)
+ head = insert_node(head, 4)
+ head = insert_node(head, 3)
+
+ print("Original list: ", end="")
+ print_linked_list(head)
+
+ places = 3
+ new_head = rotate_to_the_right(head, places)
+
+ print(f"After {places} iterations: ", end="")
+ print_linked_list(new_head)

data_structures/linked_list/rotate_to_the_right.py

@@ -0,0 +1,156 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Node:
+ data: int
+ next_node: Node | None = None
+
+
+def print_linked_list(head: Node | None) -> None:
+ """
+ Print the entire linked list iteratively.
+
+ This function prints the elements of a linked list separated by '->'.
+
+ Parameters:
+ head (Node | None): The head of the linked list to be printed,
+ or None if the linked list is empty.
+
+ >>> head = insert_node(None, 0)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 1)
+ >>> print_linked_list(head)
+ 0->2->1
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> print_linked_list(head)
+ 0->2->1->4->5
+ """
+ if head is None:
+ return
+ while head.next_node is not None:
+ print(head.data, end="->")
+ head = head.next_node
+ print(head.data)
+
+
+def insert_node(head: Node | None, data: int) -> Node:
+ """
+ Insert a new node at the end of a linked list and return the new head.
+
+ Parameters:
+ head (Node | None): The head of the linked list.
+ data (int): The data to be inserted into the new node.
+
+ Returns:
+ Node: The new head of the linked list.
+
+ >>> head = insert_node(None, 10)
+ >>> head = insert_node(head, 9)
+ >>> head = insert_node(head, 8)
+ >>> print_linked_list(head)
+ 10->9->8
+ """
+ new_node = Node(data)
+ # If the linked list is empty, the new_node becomes the head
+ if head is None:
+ return new_node
+
+ temp_node = head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+
+ temp_node.next_node = new_node # type: ignore
+ return head
+
+
+def rotate_to_the_right(head: Node, places: int) -> Node:
+ """
+ Rotate a linked list to the right by places times.
+
+ Parameters:
+ head: The head of the linked list.
+ places: The number of places to rotate.
+
+ Returns:
+ Node: The head of the rotated linked list.
+
+ >>> rotate_to_the_right(None, places=1)
+ Traceback (most recent call last):
+ ...
+ ValueError: The linked list is empty.
+ >>> head = insert_node(None, 1)
+ >>> rotate_to_the_right(head, places=1) == head
+ True
+ >>> head = insert_node(None, 1)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 3)
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> new_head = rotate_to_the_right(head, places=2)
+ >>> print_linked_list(new_head)
+ 4->5->1->2->3
+ """
+ # Check if the list is empty or has only one element
+ if not head:
+ raise ValueError("The linked list is empty.")
+
+ if head.next_node is None:
+ return head
+
+ # Calculate the length of the linked list
+ length = 1
+ temp_node = head
+ while temp_node.next_node is not None:
+ length += 1
+ temp_node = temp_node.next_node
+
+ # Adjust the value of places to avoid places longer than the list.
+ places %= length
+
+ if places == 0:
+ return head # As no rotation is needed.
+
+ # Find the new head position after rotation.
+ new_head_index = length - places
+
+ # Traverse to the new head position
+ temp_node = head
+ for _ in range(new_head_index - 1):
+ assert temp_node.next_node
+ temp_node = temp_node.next_node
+
+ # Update pointers to perform rotation
+ assert temp_node.next_node
+ new_head = temp_node.next_node
+ temp_node.next_node = None
+ temp_node = new_head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+ temp_node.next_node = head
+
+ assert new_head
+ return new_head
+
+
+if __name__ == "__main__":
+ import doctest
+
+ doctest.testmod()
+ head = insert_node(None, 5)
+ head = insert_node(head, 1)
+ head = insert_node(head, 2)
+ head = insert_node(head, 4)
+ head = insert_node(head, 3)
+
+ print("Original list: ", end="")
+ print_linked_list(head)
+
+ places = 3
+ new_head = rotate_to_the_right(head, places)
+
+ print(f"After {places} iterations: ", end="")
+ print_linked_list(new_head)

data_structures/linked_list/rotate_to_the_right.py

@@ -0,0 +1,156 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Node:
+ data: int
+ next_node: Node | None = None
+
+
+def print_linked_list(head: Node | None) -> None:
+ """
+ Print the entire linked list iteratively.
+
+ This function prints the elements of a linked list separated by '->'.
+
+ Parameters:
+ head (Node | None): The head of the linked list to be printed,
+ or None if the linked list is empty.
+
+ >>> head = insert_node(None, 0)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 1)
+ >>> print_linked_list(head)
+ 0->2->1
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> print_linked_list(head)
+ 0->2->1->4->5
+ """
+ if head is None:
+ return
+ while head.next_node is not None:
+ print(head.data, end="->")
+ head = head.next_node
+ print(head.data)
+
+
+def insert_node(head: Node | None, data: int) -> Node:
+ """
+ Insert a new node at the end of a linked list and return the new head.
+
+ Parameters:
+ head (Node | None): The head of the linked list.
+ data (int): The data to be inserted into the new node.
+
+ Returns:
+ Node: The new head of the linked list.
+
+ >>> head = insert_node(None, 10)
+ >>> head = insert_node(head, 9)
+ >>> head = insert_node(head, 8)
+ >>> print_linked_list(head)
+ 10->9->8
+ """
+ new_node = Node(data)
+ # If the linked list is empty, the new_node becomes the head
+ if head is None:
+ return new_node
+
+ temp_node = head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+
+ temp_node.next_node = new_node # type: ignore
+ return head
+
+
+def rotate_to_the_right(head: Node, places: int) -> Node:
+ """
+ Rotate a linked list to the right by places times.
+
+ Parameters:
+ head: The head of the linked list.
+ places: The number of places to rotate.
+
+ Returns:
+ Node: The head of the rotated linked list.
+
+ >>> rotate_to_the_right(None, places=1)
+ Traceback (most recent call last):
+ ...
+ ValueError: The linked list is empty.
+ >>> head = insert_node(None, 1)
+ >>> rotate_to_the_right(head, places=1) == head
+ True
+ >>> head = insert_node(None, 1)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 3)
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> new_head = rotate_to_the_right(head, places=2)
+ >>> print_linked_list(new_head)
+ 4->5->1->2->3
+ """
+ # Check if the list is empty or has only one element
+ if not head:
+ raise ValueError("The linked list is empty.")
+
+ if head.next_node is None:
+ return head
+
+ # Calculate the length of the linked list
+ length = 1
+ temp_node = head
+ while temp_node.next_node is not None:
+ length += 1
+ temp_node = temp_node.next_node
+
+ # Adjust the value of places to avoid places longer than the list.
+ places %= length
+
+ if places == 0:
+ return head # As no rotation is needed.
+
+ # Find the new head position after rotation.
+ new_head_index = length - places
+
+ # Traverse to the new head position
+ temp_node = head
+ for _ in range(new_head_index - 1):
+ assert temp_node.next_node
+ temp_node = temp_node.next_node
+
+ # Update pointers to perform rotation
+ assert temp_node.next_node
+ new_head = temp_node.next_node
+ temp_node.next_node = None
+ temp_node = new_head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+ temp_node.next_node = head
+
+ assert new_head
+ return new_head
+
+
+if __name__ == "__main__":
+ import doctest
+
+ doctest.testmod()
+ head = insert_node(None, 5)
+ head = insert_node(head, 1)
+ head = insert_node(head, 2)
+ head = insert_node(head, 4)
+ head = insert_node(head, 3)
+
+ print("Original list: ", end="")
+ print_linked_list(head)
+
+ places = 3
+ new_head = rotate_to_the_right(head, places)
+
+ print(f"After {places} iterations: ", end="")
+ print_linked_list(new_head)

data_structures/linked_list/rotate_to_the_right.py

@@ -0,0 +1,156 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Node:
+ data: int
+ next_node: Node | None = None
+
+
+def print_linked_list(head: Node | None) -> None:
+ """
+ Print the entire linked list iteratively.
+
+ This function prints the elements of a linked list separated by '->'.
+
+ Parameters:
+ head (Node | None): The head of the linked list to be printed,
+ or None if the linked list is empty.
+
+ >>> head = insert_node(None, 0)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 1)
+ >>> print_linked_list(head)
+ 0->2->1
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> print_linked_list(head)
+ 0->2->1->4->5
+ """
+ if head is None:
+ return
+ while head.next_node is not None:
+ print(head.data, end="->")
+ head = head.next_node
+ print(head.data)
+
+
+def insert_node(head: Node | None, data: int) -> Node:
+ """
+ Insert a new node at the end of a linked list and return the new head.
+
+ Parameters:
+ head (Node | None): The head of the linked list.
+ data (int): The data to be inserted into the new node.
+
+ Returns:
+ Node: The new head of the linked list.
+
+ >>> head = insert_node(None, 10)
+ >>> head = insert_node(head, 9)
+ >>> head = insert_node(head, 8)
+ >>> print_linked_list(head)
+ 10->9->8
+ """
+ new_node = Node(data)
+ # If the linked list is empty, the new_node becomes the head
+ if head is None:
+ return new_node
+
+ temp_node = head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+
+ temp_node.next_node = new_node # type: ignore
+ return head
+
+
+def rotate_to_the_right(head: Node, places: int) -> Node:
+ """
+ Rotate a linked list to the right by places times.
+
+ Parameters:
+ head: The head of the linked list.
+ places: The number of places to rotate.
+
+ Returns:
+ Node: The head of the rotated linked list.
+
+ >>> rotate_to_the_right(None, places=1)
+ Traceback (most recent call last):
+ ...
+ ValueError: The linked list is empty.
+ >>> head = insert_node(None, 1)
+ >>> rotate_to_the_right(head, places=1) == head
+ True
+ >>> head = insert_node(None, 1)
+ >>> head = insert_node(head, 2)
+ >>> head = insert_node(head, 3)
+ >>> head = insert_node(head, 4)
+ >>> head = insert_node(head, 5)
+ >>> new_head = rotate_to_the_right(head, places=2)
+ >>> print_linked_list(new_head)
+ 4->5->1->2->3
+ """
+ # Check if the list is empty or has only one element
+ if not head:
+ raise ValueError("The linked list is empty.")
+
+ if head.next_node is None:
+ return head
+
+ # Calculate the length of the linked list
+ length = 1
+ temp_node = head
+ while temp_node.next_node is not None:
+ length += 1
+ temp_node = temp_node.next_node
+
+ # Adjust the value of places to avoid places longer than the list.
+ places %= length
+
+ if places == 0:
+ return head # As no rotation is needed.
+
+ # Find the new head position after rotation.
+ new_head_index = length - places
+
+ # Traverse to the new head position
+ temp_node = head
+ for _ in range(new_head_index - 1):
+ assert temp_node.next_node
+ temp_node = temp_node.next_node
+
+ # Update pointers to perform rotation
+ assert temp_node.next_node
+ new_head = temp_node.next_node
+ temp_node.next_node = None
+ temp_node = new_head
+ while temp_node.next_node:
+ temp_node = temp_node.next_node
+ temp_node.next_node = head
+
+ assert new_head
+ return new_head
+
+
+if __name__ == "__main__":
+ import doctest
+
+ doctest.testmod()
+ head = insert_node(None, 5)
+ head = insert_node(head, 1)
+ head = insert_node(head, 2)
+ head = insert_node(head, 4)
+ head = insert_node(head, 3)
+
+ print("Original list: ", end="")
+ print_linked_list(head)
+
+ places = 3
+ new_head = rotate_to_the_right(head, places)
+
+ print(f"After {places} iterations: ", end="")
+ print_linked_list(new_head)