Consider the following structure declaration for a linked list in C:

struct node {

int data;

struct node* tail;

};

typedef struct node Node;

We represent linked lists as pointers to Node structs. Empty lists are represented with the null pointer. Non-empty lists are represented as a valid pointer to a Node, with the head data in the data field of the struct and the tail in the tail field of the struct. All lists will be assumed to be non-cyclic.

(a) Write a function to add an element to the head of the list with the following prototype. Node *cons(int n, Node *tail); [5 marks]

(b) Write a function to free the memory associated with a linked list, with the following prototype: void free_list(Node *list); [5 marks]

(c) Write a function to do an in-place list reversal. It should take a list as an argument, and return a list with the elements reversed. This function may not do any heap allocation, but may modify its input. It should have the following prototype: Node *reverse(Node *list);