You are asked to give an implementation of the ADT set using an array of Boolean and 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>
#include <stdlib.h>
#define N 100

typedef struct 
{
	char tab[N];
} SET;
void toempty(SET *e) 
{
	int i;
	for (i = 0; i < N; i++)
		e->tab[i] = 0;
}

int empty(SET e) 
{
	int i;
	for (i = 0; i < N; i++)
		if (e.tab[i] != 0)
			return 0;
	return 1;
}

int find(int x, SET e) 
{
	return e.tab[x];
}

void add(int x, SET *e) 
{
	e->tab[x] = 1;
}

void removeS(int x, SET *e) 
{
	e->tab[x] = 0;
}   

void intersect(SET e1, SET e2, SET *r) 
{
	int i;
	for (i = 0; i < N; i++)
		r->tab[i] = e1.tab[i] && e2.tab[i];
}

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

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

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