#include <stdio.h>
void subset (char * set, int * mask, int size, int c)
{
if (c == size)
{
//we get a result, output it
printf ( "{ ");
for (int i = 0; i < size; i++)
if (mask[i] == 1)
printf ( "%c ", set[i]);
printf ( "}\n ");
}
else
{
//select the cth element
mask[c] = 1;
//process the remainning elements
subset (set, mask, size, c + 1);
//unselect the cth element
mask[c] = 0;
//process the remaining elements
subset (set, mask, size, c + 1);
}
}

int main ()
{
char set[] = { 'a', 'b', 'c','d'};
int mask[4];
subset (set, mask, 4, 0);
return 0;
}

　　　　　　

我老婆，不出意外有以下集中情况:赖床。自习。给我画油画。