Add Comments (TheAlgorithms#9668)

* docs : add comment in circular_linked_list.py and swap_nodes.py

* docs : improve comments

* docs : improved docs and tested on pre-commit

* docs : add comment in circular_linked_list.py and swap_nodes.py

* docs : improve comments

* docs : improved docs and tested on pre-commit

* docs : modified comments

* Update circular_linked_list.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* docs : improved

* Update data_structures/linked_list/circular_linked_list.py

Co-authored-by: Christian Clauss <[email protected]>

* Update data_structures/linked_list/circular_linked_list.py

Co-authored-by: Christian Clauss <[email protected]>

* Update data_structures/linked_list/swap_nodes.py

Co-authored-by: Christian Clauss <[email protected]>

* Update data_structures/linked_list/swap_nodes.py

Co-authored-by: Christian Clauss <[email protected]>

* Update data_structures/linked_list/swap_nodes.py

Co-authored-by: Christian Clauss <[email protected]>

* Update data_structures/linked_list/swap_nodes.py

Co-authored-by: Christian Clauss <[email protected]>

* Update requirements.txt

Co-authored-by: Christian Clauss <[email protected]>

* Update data_structures/linked_list/circular_linked_list.py

Co-authored-by: Christian Clauss <[email protected]>

* Apply suggestions from code review

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update circular_linked_list.py

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <[email protected]>

Author: 3 people

data_structures/linked_list/circular_linked_list.py

@@ -6,16 +6,29 @@
 
 class Node:
     def __init__(self, data: Any):
+        """
+        Initialize a new Node with the given data.
+        Args:
+            data: The data to be stored in the node.
+        """
         self.data: Any = data
-        self.next: Node | None = None
+        self.next: Node | None = None  # Reference to the next node
 
 
 class CircularLinkedList:
-    def __init__(self):
-        self.head = None
-        self.tail = None
+    def __init__(self) -> None:
+        """
+        Initialize an empty Circular Linked List.
+        """
+        self.head = None  # Reference to the head (first node)
+        self.tail = None  # Reference to the tail (last node)
 
     def __iter__(self) -> Iterator[Any]:
+        """
+        Iterate through all nodes in the Circular Linked List yielding their data.
+        Yields:
+            The data of each node in the linked list.
+        """
         node = self.head
         while self.head:
             yield node.data
@@ -24,25 +37,48 @@ def __iter__(self) -> Iterator[Any]:
                 break
 
     def __len__(self) -> int:
+        """
+        Get the length (number of nodes) in the Circular Linked List.
+        """
         return sum(1 for _ in self)
 
-    def __repr__(self):
+    def __repr__(self) -> str:
+        """
+        Generate a string representation of the Circular Linked List.
+        Returns:
+            A string of the format "1->2->....->N".
+        """
         return "->".join(str(item) for item in iter(self))
 
     def insert_tail(self, data: Any) -> None:
+        """
+        Insert a node with the given data at the end of the Circular Linked List.
+        """
         self.insert_nth(len(self), data)
 
     def insert_head(self, data: Any) -> None:
+        """
+        Insert a node with the given data at the beginning of the Circular Linked List.
+        """
         self.insert_nth(0, data)
 
     def insert_nth(self, index: int, data: Any) -> None:
+        """
+        Insert the data of the node at the nth pos in the Circular Linked List.
+        Args:
+            index: The index at which the data should be inserted.
+            data: The data to be inserted.
+
+        Raises:
+            IndexError: If the index is out of range.
+        """
         if index < 0 or index > len(self):
             raise IndexError("list index out of range.")
         new_node = Node(data)
         if self.head is None:
-            new_node.next = new_node  # first node points itself
+            new_node.next = new_node  # First node points to itself
             self.tail = self.head = new_node
-        elif index == 0:  # insert at head
+        elif index == 0:  # Insert at the head
             new_node.next = self.head
             self.head = self.tail.next = new_node
         else:
@@ -51,22 +87,43 @@ def insert_nth(self, index: int, data: Any) -> None:
                 temp = temp.next
             new_node.next = temp.next
             temp.next = new_node
-            if index == len(self) - 1:  # insert at tail
+            if index == len(self) - 1:  # Insert at the tail
                 self.tail = new_node
 
-    def delete_front(self):
+    def delete_front(self) -> Any:
+        """
+        Delete and return the data of the node at the front of the Circular Linked List.
+        Raises:
+            IndexError: If the list is empty.
+        """
         return self.delete_nth(0)
 
     def delete_tail(self) -> Any:
+        """
+        Delete and return the data of the node at the end of the Circular Linked List.
+        Returns:
+            Any: The data of the deleted node.
+        Raises:
+            IndexError: If the index is out of range.
+        """
         return self.delete_nth(len(self) - 1)
 
     def delete_nth(self, index: int = 0) -> Any:
+        """
+        Delete and return the data of the node at the nth pos in Circular Linked List.
+        Args:
+            index (int): The index of the node to be deleted. Defaults to 0.
+        Returns:
+            Any: The data of the deleted node.
+        Raises:
+            IndexError: If the index is out of range.
+        """
         if not 0 <= index < len(self):
             raise IndexError("list index out of range.")
         delete_node = self.head
-        if self.head == self.tail:  # just one node
+        if self.head == self.tail:  # Just one node
             self.head = self.tail = None
-        elif index == 0:  # delete head node
+        elif index == 0:  # Delete head node
             self.tail.next = self.tail.next.next
             self.head = self.head.next
         else:
@@ -75,16 +132,22 @@ def delete_nth(self, index: int = 0) -> Any:
                 temp = temp.next
             delete_node = temp.next
             temp.next = temp.next.next
-            if index == len(self) - 1:  # delete at tail
+            if index == len(self) - 1:  # Delete at tail
                 self.tail = temp
         return delete_node.data
 
     def is_empty(self) -> bool:
+        """
+        Check if the Circular Linked List is empty.
+        Returns:
+            bool: True if the list is empty, False otherwise.
+        """
         return len(self) == 0
 
 
 def test_circular_linked_list() -> None:
     """
+    Test cases for the CircularLinkedList class.
     >>> test_circular_linked_list()
     """
     circular_linked_list = CircularLinkedList()

data_structures/linked_list/swap_nodes.py

@@ -2,30 +2,56 @@
 
 
 class Node:
-    def __init__(self, data: Any):
+    def __init__(self, data: Any) -> None:
+        """
+        Initialize a new Node with the given data.
+
+        Args:
+            data: The data to be stored in the node.
+
+        """
         self.data = data
-        self.next = None
+        self.next = None  # Reference to the next node
 
 
 class LinkedList:
-    def __init__(self):
-        self.head = None
+    def __init__(self) -> None:
+        """
+        Initialize an empty Linked List.
+        """
+        self.head = None  # Reference to the head (first node)
 
     def print_list(self):
+        """
+        Print the elements of the Linked List in order.
+        """
         temp = self.head
         while temp is not None:
             print(temp.data, end=" ")
             temp = temp.next
         print()
 
-    # adding nodes
-    def push(self, new_data: Any):
+    def push(self, new_data: Any) -> None:
+        """
+        Add a new node with the given data to the beginning of the Linked List.
+        Args:
+            new_data (Any): The data to be added to the new node.
+        """
         new_node = Node(new_data)
         new_node.next = self.head
         self.head = new_node
 
-    # swapping nodes
-    def swap_nodes(self, node_data_1, node_data_2):
+    def swap_nodes(self, node_data_1, node_data_2) -> None:
+        """
+        Swap the positions of two nodes in the Linked List based on their data values.
+        Args:
+            node_data_1: Data value of the first node to be swapped.
+            node_data_2: Data value of the second node to be swapped.
+
+
+        Note:
+            If either of the specified data values isn't found then, no swapping occurs.
+        """
         if node_data_1 == node_data_2:
             return
         else:
@@ -40,6 +66,7 @@ def swap_nodes(self, node_data_1, node_data_2):
             if node_1 is None or node_2 is None:
                 return
 
+            # Swap the data values of the two nodes
             node_1.data, node_2.data = node_2.data, node_1.data
 
 
@@ -48,8 +75,10 @@ def swap_nodes(self, node_data_1, node_data_2):
     for i in range(5, 0, -1):
         ll.push(i)
 
+    print("Original Linked List:")
     ll.print_list()
 
     ll.swap_nodes(1, 4)
-    print("After swapping")
+    print("After swapping the nodes whose data is 1 and 4:")
+
     ll.print_list()