To insert a new node at the beginning of a linked list, you first create a new node with the data you want to insert. Then, you make the new node's next pointer point to the current head of the linked list. Finally, you make the head of the linked list point to the new node.
The time complexity of inserting a node at the beginning of a linked list is O(1). This is because you only need to perform a few constant time operations to insert the new node, regardless of the size of the linked list.
To insert a new node at the end of a linked list, you first traverse to the end of the linked list by following the next pointers until you reach the last node. Then, you make the last node's next pointer point to the new node, and you make the new node's next pointer point to null.
The time complexity of inserting a node at the end of a linked list is O(n), where n is the number of nodes in the linked list. This is because you need to traverse through the entire linked list to reach the end.
To insert a new node at a specific position in a linked list, you first traverse to the node at the position before the desired position. Then, you make the new node's next pointer point to the next node, and you make the previous node's next pointer point to the new node.