single link list.py

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

class LinkedList:
    def __init__(self):
        self.head = None

    def insertAtBeginning(self, data):
        new_node = Node(data)
        new_node.next = self.head
        self.head = new_node

    def insertAtEnd(self, data):
        new_node = Node(data)
        if self.head is None:
            self.head = new_node
            return
        last = self.head
        while last.next:
            last = last.next
        last.next = new_node

    def insertAfter(self, prev_node, data):
        if prev_node is None:
            return
        new_node = Node(data)
        new_node.next = prev_node.next
        prev_node.next = new_node

    def deleteNode(self, position):
        if self.head is None:
            return
        temp = self.head
        if position == 0:
            self.head = temp.next
            temp = None
            return
        for _ in range(position - 1):
            temp = temp.next
            if temp is None or temp.next is None:
                return
        next = temp.next.next
        temp.next = None
        temp.next = next

    def display(self):
        temp = self.head
        while temp:
            print(temp.data, end=" -> ")
            temp = temp.next
        print("None")

if __name__ == "__main__":
    llist = LinkedList()
    llist.insertAtBeginning(10)
    llist.insertAtEnd(20)
    llist.insertAtEnd(30)
    llist.insertAfter(llist.head.next, 25)
    llist.display()
    llist.deleteNode(2)
    llist.display()