linked list reverse without temp

Question

Is there any way to reverse linked list without using temp variable in C? Thanks in advance.

the famous approach:

Element *reverse(Element *head)
{
    Element *previous = NULL;

    while (head != NULL) {
        // Keep next node since we trash
        // the next pointer.
        Element *next = head->next;

        // Switch the next pointer
        // to point backwards.
        head->next = previous;

        // Move both pointers forward.
        previous = head;
        head = next;
    }

    return previous;
}

uses temp variable

Saurabh

Answer 1

Note that your temp usage is actually generating two swap() calls, and can be replaced with:

swap(head->next,previous);
swap(previous,head);

You can swap without temps using xor, it is called xor swap.