You are asked to give a static implementation of the ADT set having the following functions:

• void toempty(SET *S)
• int empty(SET S)
• int find(int x, SET S)
• void add(int x, SET *S)
• void removeS(int x, SET *S)
• void intersect(SET S1, SET S2, SET *R)
• void unionS(SET S1, SET S2, SET *R)
• void complement(SET S, SET *R)
• void display(SET S)

#include <stdio.h>
#define N 100

typedef struct 
{
	int nbr;
	int tab[N];
} SET;

void toempty(SET *e) 
{
	e->nbr = 0;
}

int empty(SET e) 
{
	return e.nbr == 0;
}

int find(int x, SET e) 
{
	int i = 0;
 	while (i < e.nbr && e.tab[i] != x)
		i++;
	return i < e.nbr;
}

void add(int x, SET *e) 
{
	if ( ! find(x, *e))
		e->tab[e->nbr++] = x;
}

void removeS(int x, SET *e) 
{
	int i = 0;
	while (i < e->nbr && e->tab[i] != x)
		i++;
	if (i < e->nbr)
		e->tab[i] = e->tab[--e->nbr];
}   

void intersect(SET e1, SET e2, SET *r) 
{
	int i, x;
	toempty(r);
	for (i = 0; i < e1.nbr; i++) 
	{
		x = e1.tab[i];
		if (find(x, e2))
			add(x, r);
	}
}

void unionS(SET e1, SET e2, SET *r) 
{
	int i;
	*r = e2;
	for (i = 0; i < e1.nbr; i++)
		add(e1.tab[i], r);
}

void complement(SET e, SET *r) 
{
	int i, k;
	for (i = 0; i < N; i++)
		r->tab[i] = i;
	for (i = 0; i < e.nbr; i++)
		r->tab[e.tab[i]] = -1;
	k = 0;
	for (i = 0; i < N; i++)
		if (r->tab[i] >= 0)
			r->tab[k++] = r->tab[i];
	r->nbr = k;
}

void display(SET e) 
{
	int i;
    
	printf("[ ");
	for (i = 0; i < e.nbr; i++)
		printf("%d ", e.tab[i]); 
	printf("]");
}


int main() 
{
	SET a, b, c;
	int i;
    
	toempty(&a);
	for (i = 0; i < 32; i += 2)
		add(i, &a);
	for (i = 30; i >= 0; i -= 3)
		add(i, &a);
	printf("  a : "); 
	display(a); 
	printf("\n");
    
	toempty(&b);
	printf("a empty? %s\n", empty(a) ? "yes" : "no");    
	printf("b empty? %s\n", empty(b) ? "yes" : "no");
	for (i = 0; i < 32; i += 5)
		add(i, &b);
	printf("  b : "); 
	display(b); 
	printf("\n");
    
	complement(b, &c);
	printf(" ~b : "); 
	display(c); 
	printf("\n");
    
	intersect(a, b, &c);
	printf("a.b : "); 
	display(c); 
	printf("\n");
    
	unionS(a, b, &c);
	printf("a+b : "); 
	display(c); 
	printf("\n");
  
	for (i = 0; i < 32; i += 3)
		removeS(i, &c);
	printf("c : "); 
	display(c); 
	printf("\n");
    
	return 0;
}