Push Front

Inserting at the Front

Adding a node to the front of a list is O(1) — the cheapest insertion in a linked list.

Create the new node, point its next to the current head, and return it as the new head:

struct Node *push_front(struct Node *head, int val) {
    struct Node *n = new_node(val);
    n->next = head;
    return n;
}

Before: [2] -> [3] -> NULL
After:  [1] -> [2] -> [3] -> NULL   (push_front(head, 1))

Why Return the New Head?

In C, if we just modify n->next, the caller's head variable still points to the old first node. We must return the new node and let the caller update their pointer:

head = push_front(head, 10);

Push Order

Calling push_front repeatedly builds the list in reverse order:

head = push_front(NULL, 1);  // [1]
head = push_front(head, 2);  // [2] -> [1]
head = push_front(head, 3);  // [3] -> [2] -> [1]

Your Task

Implement struct Node *push_front(struct Node *head, int val) that prepends a node and returns the new head.