#include <stdio.h>
void printPowerSet(char *set, int l , int h , int size)
{
int i=l;
for(i=l;i<=h;i++){printf("%c",set[i]);}
printf("\n");
if(l+1 < size){ printPowerSet(set,l+1,h,size); }
if(h-1 >= 0 ){printPowerSet(set,l,h-1,size);}
if( l+1<size && h-1 >=0) {printPowerSet(set,l+1,h-1,size);}
}//printpowerset
int main(void) {
char set[] = {'a','b','c'};
    printPowerSet(set,0,2,3 );

    getchar();
 
	return 0;
}