Merge pull request #3 from mcleber/main

Update

Author: mcleber

README.md

@@ -10,6 +10,7 @@ This is my study repository.
 * circular queue.
 * priority queue.
 * deque (double-ended queue).
+* singly linked list.
 
 
 ## Link

src/singly_linked_list.py

@@ -0,0 +1,163 @@
+#!/usr/bin/env python3
+
+##
+# Singly Linked List
+##
+
+import numpy as np
+
+class Node:
+    """
+    A class representing a node in a linked list.
+
+    Attributes:
+    value (int): The value stored in the node.
+    next (Node): A reference to the next node in the list.
+    """
+    def __init__(self, value):
+        """
+        Initializes the node with a given value and sets the next reference to None.
+
+        Args:
+        value (int): The value to be stored in the node.
+        """
+        self.value = value
+        self.next = None
+
+    def show_node(self):
+        """
+        Prints the value of the node.
+        """
+        print(self.value)
+
+
+class LinkedList:
+    """
+    A class representing a singly linked list.
+
+    Attributes:
+    first (Node): The first node in the linked list.
+    """
+    def __init__(self):
+        """
+        Initializes an empty linked list with no nodes.
+        """
+        self.first = None
+
+    def insert_start(self, value):
+        """
+        Inserts a new node with the given value at the start of the list.
+
+        Args:
+        value (int): The value to be inserted at the start of the list.
+        """
+        new_node = Node(value)
+        new_node.next = self.first
+        self.first = new_node
+
+    def display(self):
+        """
+        Displays the values of all nodes in the list.
+        If the list is empty, it prints a message indicating so.
+        """
+        if self.first is None:
+            print('The list is empty')
+            return None
+
+        current = self.first
+        while current is not None:
+            current.show_node()
+            current = current.next
+
+    def search(self, value):
+        """
+        Searches for a node with the given value in the list.
+
+        Args:
+        value (int): The value to search for.
+
+        Returns:
+        Node: The node containing the value, or None if not found.
+        """
+        if self.first is None:
+            print('The list is empty')
+            return None
+
+        current = self.first
+        while current.value != value:
+            if current.next is None:
+                return None
+            else:
+                current = current.next
+        return current
+
+    def delete_start(self):
+        """
+        Deletes the first node from the list.
+
+        Returns:
+        Node: The node that was deleted, or None if the list is empty.
+        """
+        if self.first is None:
+            print('The list is empty')
+            return None
+
+        temp = self.first
+        self.first = self.first.next
+        return temp
+
+    def delete_position(self, value):
+        """
+        Deletes a node with the given value from the list.
+
+        Args:
+        value (int): The value of the node to delete.
+
+        Returns:
+        Node: The node that was deleted, or None if not found.
+        """
+        if self.first is None:
+            print('The list is empty')
+            return None
+
+        current = self.first
+        previous = self.first
+        while current.value != value:
+            if current.next is None:
+                return None
+            else:
+                previous = current
+                current = current.next
+
+        if current == self.first:
+            self.first = self.first.next
+        else:
+            previous.next = current.next
+
+        return current
+
+
+# Tests
+linked_list = LinkedList()
+linked_list.insert_start(1)
+linked_list.insert_start(2)
+linked_list.insert_start(3)
+linked_list.insert_start(4)
+linked_list.insert_start(5)
+
+linked_list.display()
+
+print(20 * '-')
+
+search_result = linked_list.search(3)
+
+linked_list.delete_start()
+linked_list.delete_position(4)
+linked_list.delete_position(2)
+
+linked_list.display()
+
+
+
+
+