Swapping linked list pairs with two pointers

llswap.cpp

#include <cstdio>

struct Node {
    int data;
    Node* next;
};

Node* makeList(int count)
{
    Node* const head = new Node();
    Node* prev = head;

    head->data = 1;

    for (int i = 1; i < count; ++i) {
        Node* nn = new Node();
        nn->data = i + 1;
        prev->next = nn;
        prev = nn;
    }
    return head;
}

void walk(Node* head)
{
    while (head != nullptr) {
        printf("%d\n", head->data);
        head = head->next;
    }
}

// The interesting bit
// Double-pointer magic borrowed form Linus (he's smart):
// http://stackoverflow.com/questions/12914917/using-pointers-to-remove-item-from-singly-linked-list
void swapPairs(Node** n)
{
    // There must be another two to swap
    while(*n != nullptr && (*n)->next != nullptr) {
        // Get a pointer to the node that follows this pair
        Node* const afterPair = (*n)->next->next;

        // Assign the second node's "next" to the first node
        (*n)->next->next = *n;
        // Assign the pointer to the first node to the second node
        *n = (*n)->next;
        // Assign the first node's "next" to the node after these two
        (*n)->next->next = afterPair;

        // Advance two
        n = &((*n)->next->next);
    }
}

int main()
{
    Node* head = makeList(5);
    printf("Originally:\n");
    walk(head);

    swapPairs(&head);

    printf("\nAfter:\n");
    walk(head);

    return 0;
}

/* prints
Originally:
1
2
3
4
5

After:
2
1
4
3
5
*/