Swapping the odd and even position in a linked list

A simple and intuitive solution to the problem !! It might not be very efficient but it does certainly work.


node* swap(node *head)
{
    node dummy;
    node *prev, *curr, *u, *tmp;

    if (head==NULL) return head;

    prev=&dummy;
    for(curr=head; curr!=NULL && curr->next!=NULL; ) {
        u = curr->next;
        tmp = u->next;
        prev->next = u;
        u->next = curr;
        prev = curr;
        curr = tmp;
    }
    prev->next = curr;
    return dummy.next;
}

void print(const node *head)
{
    for(const node *p=head; p; p=p->next)
        printf("%d ", p->val);
    putchar('\n');
}