#include <stdio.h>

#include <stdlib.h>

struct node { int key; struct node *next; };

struct node *head, *z, *t;

void listinitialize() {

head = (struct node *) malloc(sizeof(*head));

z = (struct node *) malloc(sizeof(*z));

head->next = z; z->next = z;

}

void deletenext(struct node *x)

{

t = x->next;

x->next = x->next->next;

free(t);

}

struct node* insertafter(int v, struct node* t)

{

struct node* x = (struct node*) malloc(sizeof(struct node));

x->key = v;

x->next = t->next;

t->next = x;

return x;

}

void printkeys()

{

t = head->next;

while(t->next != t) {

printf("%d ", t->key);

t = t->next;

}

}

void movenexttofront(struct node* x)

{

t = x->next;

x->next = x->next->next;

t->next = head->next;

head->next = t;

}

void exchange(struct node *t, struct node *u)

{

struct node *x, *y;

x = t->next;

y = u->next;

t->next = t->next->next;

u->next = u->next->next;

y->next = t->next; t->next = y;

x->next = u->next; u->next = x;

}

int main(int argc, char* argv[])

{

struct node *ptr1, *ptr2;

listinitialize();

ptr1 = insertafter(1, head);

ptr2 = insertafter(2, ptr1);

ptr1 = insertafter(3, ptr2);

printkeys(); printf("\n");

exchange(head, ptr2);

printkeys(); printf("\n");

movenexttofront(ptr2);

printkeys(); printf("\n");

deletenext(head);

printkeys();

return 0;

}