create remove_duplicates.py

data_structures/linked_list/remove_duplicates.py

@@ -0,0 +1,145 @@
+from typing import List, Optional
+
+
+class Node:
+    def __init__(self, data: int):
+        self.data = data
+        self.next = None
+
+
+def create(A: List[int]) -> Optional[Node]:
+    """
+    Create a linked list from an array.
+
+    Args:
+        A (List[int]): The input array.
+
+    Returns:
+        Optional[Node]: The head of the linked list.
+
+    Example:
+        >>> A = [1, 3, 5, 7, 9, 11, 11, 15, 17, 19]
+        >>> head = create(A)
+        >>> display(head)
+        1 3 5 7 9 11 15 17 19
+    """
+    if not A:
+        return None
+
+    head = Node(A[0])
+    last = head
+
+    for data in A[1:]:
+        last.next = Node(data)
+        last = last.next
+
+    return head
+
+
+def display(head: Optional[Node]) -> None:
+    """
+    Display the elements of a linked list.
+
+    Args:
+        head (Optional[Node]): The head of the linked list.
+
+    Example:
+        >>> A = [1, 3, 5, 7, 9, 11, 11, 15, 17, 19]
+        >>> head = create(A)
+        >>> display(head)
+        1 3 5 7 9 11 11 15 17 19
+    """
+    while head:
+        print(head.data, end=" ")
+        head = head.next
+    print()
+
+
+def count(head: Optional[Node]) -> int:
+    """
+    Count the number of nodes in a linked list.
+
+    Args:
+        head (Optional[Node]): The head of the linked list.
+
+    Returns:
+        int: The count of nodes.
+
+    Example:
+        >>> A = [1, 3, 5, 7, 9, 11, 11, 15, 17, 19]
+        >>> head = create(A)
+        >>> count(head)
+        10
+    """
+    count = 0
+    while head:
+        count += 1
+        head = head.next
+    return count
+
+
+def delete(head: Optional[Node], index: int) -> int:
+    """
+    Delete a node at a given index from a linked list.
+
+    Args:
+        head (Optional[Node]): The head of the linked list.
+        index (int): The index at which the node should be deleted (1-based index).
+
+    Returns:
+        int: The data of the deleted node, or -1 if the index is out of range.
+
+    Example:
+        >>> A = [1, 3, 5, 7, 9, 11, 11, 15, 17, 19]
+        >>> head = create(A)
+        >>> delete(head, 3)
+        5
+    """
+    if index < 1 or index > count(head):
+        return -1
+
+    if index == 1:
+        data = head.data
+        head = head.next
+        return data
+    else:
+        prev = head
+        current = head
+        for _ in range(index - 1):
+            prev = current
+            current = current.next
+        data = current.data
+        prev.next = current.next
+        return data
+
+
+def remove_duplicates(head: Optional[Node]) -> None:
+    """
+    Remove duplicate elements from a sorted linked list.
+
+    Args:
+        head (Optional[Node]): The head of the linked list.
+
+    Example:
+        >>> A = [1, 3, 3, 5, 5, 7, 7, 9]
+        >>> head = create(A)
+        >>> remove_duplicates(head)
+        >>> display(head)
+        1 3 5 7 9
+    """
+    current = head
+    while current and current.next:
+        if current.data == current.next.data:
+            current.next = current.next.next
+        else:
+            current = current.next
+
+
+if __name__ == "__main__":
+    print("Linked List!")
+
+    A = [1, 3, 5, 7, 9, 11, 11, 15, 17, 19]
+    head = create(A)
+
+    remove_duplicates(head)
+    display(head)