0x13. C - More singly linked lists; ALX: 2. Add node

Write a function that adds a new node at the beginning of a listint_t list.

Prototype: listint_t *add_nodeint(listint_t **head, const int n);
Return: the address of the new element, or NULL if it failed

All 0x13. C - More singly linked lists videos

0. Print list
1. List length
2. Add node
3. Add node at the end
4. Free list
5. Free