mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-25 05:51:08 +00:00
c9b4b8002f
* added addAtPosition to simple linked list * added addAtPosition to simple linked list * modified the add function to take an optional position command * fixed type safety errors: * fixed type safety errors: * fixed type safety errors: * fixed type safety errors: * fixed size error * fixed size error * added doctest and updates the else after checking if posiiton argument less than 0 or not * added doctest and updates the else after checking if posiiton argument less than 0 or not * fixed the contributing.md mistake * added doctest for out of bounds position value, both negative and positive
133 lines
3.7 KiB
Python
133 lines
3.7 KiB
Python
"""
|
|
Linked Lists consists of Nodes.
|
|
Nodes contain data and also may link to other nodes:
|
|
- Head Node: First node, the address of the
|
|
head node gives us access of the complete list
|
|
- Last node: points to null
|
|
"""
|
|
from __future__ import annotations
|
|
|
|
from typing import Any
|
|
|
|
|
|
class Node:
|
|
def __init__(self, item: Any, next: Any) -> None: # noqa: A002
|
|
self.item = item
|
|
self.next = next
|
|
|
|
|
|
class LinkedList:
|
|
def __init__(self) -> None:
|
|
self.head: Node | None = None
|
|
self.size = 0
|
|
|
|
def add(self, item: Any, position: int = 0) -> None:
|
|
"""
|
|
Add an item to the LinkedList at the specified position.
|
|
Default position is 0 (the head).
|
|
|
|
Args:
|
|
item (Any): The item to add to the LinkedList.
|
|
position (int, optional): The position at which to add the item.
|
|
Defaults to 0.
|
|
|
|
Raises:
|
|
ValueError: If the position is negative or out of bounds.
|
|
|
|
>>> linked_list = LinkedList()
|
|
>>> linked_list.add(1)
|
|
>>> linked_list.add(2)
|
|
>>> linked_list.add(3)
|
|
>>> linked_list.add(4, 2)
|
|
>>> print(linked_list)
|
|
3 --> 2 --> 4 --> 1
|
|
|
|
# Test adding to a negative position
|
|
>>> linked_list.add(5, -3)
|
|
Traceback (most recent call last):
|
|
...
|
|
ValueError: Position must be non-negative
|
|
|
|
# Test adding to an out-of-bounds position
|
|
>>> linked_list.add(5,7)
|
|
Traceback (most recent call last):
|
|
...
|
|
ValueError: Out of bounds
|
|
>>> linked_list.add(5, 4)
|
|
>>> print(linked_list)
|
|
3 --> 2 --> 4 --> 1 --> 5
|
|
"""
|
|
if position < 0:
|
|
raise ValueError("Position must be non-negative")
|
|
|
|
if position == 0 or self.head is None:
|
|
new_node = Node(item, self.head)
|
|
self.head = new_node
|
|
else:
|
|
current = self.head
|
|
for _ in range(position - 1):
|
|
current = current.next
|
|
if current is None:
|
|
raise ValueError("Out of bounds")
|
|
new_node = Node(item, current.next)
|
|
current.next = new_node
|
|
self.size += 1
|
|
|
|
def remove(self) -> Any:
|
|
# Switched 'self.is_empty()' to 'self.head is None'
|
|
# because mypy was considering the possibility that 'self.head'
|
|
# can be None in below else part and giving error
|
|
if self.head is None:
|
|
return None
|
|
else:
|
|
item = self.head.item
|
|
self.head = self.head.next
|
|
self.size -= 1
|
|
return item
|
|
|
|
def is_empty(self) -> bool:
|
|
return self.head is None
|
|
|
|
def __str__(self) -> str:
|
|
"""
|
|
>>> linked_list = LinkedList()
|
|
>>> linked_list.add(23)
|
|
>>> linked_list.add(14)
|
|
>>> linked_list.add(9)
|
|
>>> print(linked_list)
|
|
9 --> 14 --> 23
|
|
"""
|
|
if self.is_empty():
|
|
return ""
|
|
else:
|
|
iterate = self.head
|
|
item_str = ""
|
|
item_list: list[str] = []
|
|
while iterate:
|
|
item_list.append(str(iterate.item))
|
|
iterate = iterate.next
|
|
|
|
item_str = " --> ".join(item_list)
|
|
|
|
return item_str
|
|
|
|
def __len__(self) -> int:
|
|
"""
|
|
>>> linked_list = LinkedList()
|
|
>>> len(linked_list)
|
|
0
|
|
>>> linked_list.add("a")
|
|
>>> len(linked_list)
|
|
1
|
|
>>> linked_list.add("b")
|
|
>>> len(linked_list)
|
|
2
|
|
>>> _ = linked_list.remove()
|
|
>>> len(linked_list)
|
|
1
|
|
>>> _ = linked_list.remove()
|
|
>>> len(linked_list)
|
|
0
|
|
"""
|
|
return self.size
|