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Merged
wahreus merged 1 commit into from
Jun 7, 2026
Merged

Added non-interactive SLL #14

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1 change: 1 addition & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@ A repo for storing Python code and tracking learning progress. All programs are
└── data_structures
├── doubly_linked_list-interactive.py
├── doubly_linked_list.py
├── singly_linked_list-interactive.py
└── singly_linked_list.py
```

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149 changes: 149 additions & 0 deletions data_structures/singly_linked_list-interactive.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,149 @@
"""A singly linked list implementation with an interactive command-line menu."""


from dataclasses import dataclass
import os


@dataclass
class Node:
data: int
next: "Node | None" = None


class SinglyLinkedList:
def __init__(self, items: list[int]) -> None:
self.head: Node | None = None
self.tail: Node | None = None
current: Node | None = None
for item in items:
new_node = Node(item)
if current is None:
self.head = new_node
else:
current.next = new_node
current = new_node
self.tail = current

def append(self, item: int) -> None:
new_node = Node(item)
if self.head is None:
self.head = new_node
self.tail = new_node
return
assert self.tail is not None
self.tail.next = new_node
self.tail = new_node

def __len__(self) -> int:
size = 0
current = self.head
while current is not None:
size += 1
current = current.next
return size

def print_list(self) -> None:
if self.head is None:
print("(empty)")
return
current = self.head
values: list[str] = []
while current is not None:
values.append(str(current.data))
current = current.next
print(" ".join(values))

def remove(self, item: int) -> bool:
if self.head is None:
return False
if self.head.data == item:
self.head = self.head.next
if self.head is None:
self.tail = None
return True
current = self.head
while current.next is not None:
if current.next.data == item:
removed_node = current.next
current.next = removed_node.next
if removed_node is self.tail:
self.tail = current
return True
current = current.next
return False

def sort_list(self) -> None:
values: list[int] = []
current = self.head
while current is not None:
values.append(current.data)
current = current.next
values.sort()
sorted_list = SinglyLinkedList(values)
self.head = sorted_list.head
self.tail = sorted_list.tail


def clear_screen() -> None:
os.system("cls" if os.name == "nt" else "clear")


def command_loop(linked_list: SinglyLinkedList) -> None:
clear_screen()
while True:
print("Current list: ", end="")
linked_list.print_list()
print("__________________")
command = input(
"Command options:\n"
" 1 append item\n"
" 2 remove item\n"
" 3 count items\n"
" 4 sort list\n"
" 5 exit\n"
"__________________\n"
"Command: ")

if command == "1":
try:
item = int(input("\nEnter item to append: "))
linked_list.append(item)
except ValueError:
input(" - Please enter a valid integer.\n - Press Enter to continue.")

elif command == "2":
try:
item = int(input("\nEnter item to remove: "))
removed = linked_list.remove(item)
if not removed:
input(" - No matching item found.\n - Press Enter to continue.")
except ValueError:
input(" - Please enter a valid integer.\n - Press Enter to continue.")

elif command == "3":
size = len(linked_list)
word = "item" if size == 1 else "items"
input(f"\n - The list contains {size} {word}.\n - Press Enter to continue.")

elif command == "4":
linked_list.sort_list()

elif command == "5":
print("\n - Goodbye!\n")
break

else:
input(" - Invalid command.\n - Press Enter to continue.")

clear_screen()


def main() -> None:
numbers = [4, 2, 7, 1, 9, 6, 5, 8, 3]
linked_list = SinglyLinkedList(numbers)
command_loop(linked_list)


if __name__ == "__main__":
main()
150 changes: 50 additions & 100 deletions data_structures/singly_linked_list.py
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Original file line number Diff line number Diff line change
@@ -1,8 +1,7 @@
"""A singly linked list implementation with an interactive command-line menu."""
"""A singly linked list implementation."""


from dataclasses import dataclass
import os


@dataclass
Expand All @@ -15,15 +14,8 @@ class SinglyLinkedList:
def __init__(self, items: list[int]) -> None:
self.head: Node | None = None
self.tail: Node | None = None
current: Node | None = None
for item in items:
new_node = Node(item)
if current is None:
self.head = new_node
else:
current.next = new_node
current = new_node
self.tail = current
self.append(item)

def append(self, item: int) -> None:
new_node = Node(item)
Expand All @@ -35,114 +27,72 @@ def append(self, item: int) -> None:
self.tail.next = new_node
self.tail = new_node

def __len__(self) -> int:
size = 0
def remove(self, item: int) -> bool:
current = self.head
previous: Node | None = None
while current is not None:
size += 1
if current.data == item:
if previous is None:
self.head = current.next
else:
previous.next = current.next
if current is self.tail:
self.tail = previous
return True
previous = current
current = current.next
return size
return False

def print_list(self) -> None:
if self.head is None:
print("(empty)")
return
def sort_list(self) -> None:
values: list[int] = []
current = self.head
values: list[str] = []
while current is not None:
values.append(str(current.data))
values.append(current.data)
current = current.next
print(" ".join(values))
values.sort()
self.head = None
self.tail = None
for value in values:
self.append(value)

def remove(self, item: int) -> bool:
def fetch_list(self) -> str:
if self.head is None:
return False
if self.head.data == item:
self.head = self.head.next
if self.head is None:
self.tail = None
return True
return "(empty)"
values: list[str] = []
current = self.head
while current.next is not None:
if current.next.data == item:
removed_node = current.next
current.next = removed_node.next
if removed_node is self.tail:
self.tail = current
return True
while current is not None:
values.append(str(current.data))
current = current.next
return False
return " ".join(values)

def sort_list(self) -> None:
values: list[int] = []
def size(self) -> int:
size = 0
current = self.head
while current is not None:
values.append(current.data)
size += 1
current = current.next
values.sort()
sorted_list = SinglyLinkedList(values)
self.head = sorted_list.head
self.tail = sorted_list.tail


def clear_screen() -> None:
os.system("cls" if os.name == "nt" else "clear")


def command_loop(linked_list: SinglyLinkedList) -> None:
clear_screen()
while True:
print("Current list: ", end="")
linked_list.print_list()
print("__________________")
command = input(
"Command options:\n"
" 1 append item\n"
" 2 remove item\n"
" 3 count items\n"
" 4 sort list\n"
" 5 exit\n"
"__________________\n"
"Command: ")

if command == "1":
try:
item = int(input("\nEnter item to append: "))
linked_list.append(item)
except ValueError:
input(" - Please enter a valid integer.\n - Press Enter to continue.")

elif command == "2":
try:
item = int(input("\nEnter item to remove: "))
removed = linked_list.remove(item)
if not removed:
input(" - No matching item found.\n - Press Enter to continue.")
except ValueError:
input(" - Please enter a valid integer.\n - Press Enter to continue.")

elif command == "3":
size = len(linked_list)
word = "item" if size == 1 else "items"
input(f"\n - The list contains {size} {word}.\n - Press Enter to continue.")

elif command == "4":
linked_list.sort_list()

elif command == "5":
print("\n - Goodbye!\n")
break

else:
input(" - Invalid command.\n - Press Enter to continue.")

clear_screen()
return size


def main() -> None:
numbers = [4, 2, 7, 1, 9, 6, 5, 8, 3]
linked_list = SinglyLinkedList(numbers)
command_loop(linked_list)
linked_list = SinglyLinkedList([4, 2, 7, 1, 9, 6, 5, 8, 3])

print("Original list:")
print(linked_list.fetch_list())

linked_list.append(10)
print("\nAfter appending 10:")
print(linked_list.fetch_list())

linked_list.remove(7)
print("\nAfter removing 7:")
print(linked_list.fetch_list())

print(f"\nLength:\n{linked_list.size()}")

linked_list.sort_list()
print("\nSorted list:")
print(linked_list.fetch_list())


if __name__ == "__main__":
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