List All Of The Subsets

Problem description:Please list all of the subsets of a known set including the empty set.

My idea: one thinking of the algorithm backtracking is to generate a tree of subset and the condition of an element in the super set for a subset is either on or off.Hence we can specialize the subset tree to a binary tree and we print once when we reach the bottom of the tree each time.It is also easy to write a program.

#include <stdio.h>
  #define MAX 1000

  int n=3;  //the number of the set elements
  int set[MAX]={1,2,3};
  int count=0;//the number of the subset.

  void DFS(int level);
  void print_set();

  int main()
  {
      DFS(0);
      return 0;
  }

  void DFS(int level)
  {
      if(level==n)
      {
          print_set();
          return ;
      }
      int save=set[level];
      set[level]=0;
      int index=0;
      for(index=0;index<2;index++)
      {
          DFS(level+1);
          set[level]=save;
      }

  }

  void print_set()
  {
      int index;
      count++;
      printf("%d: {",count);
      for(index=0;index<n;index++)
      {
          if(set[index]!=0)
              printf("%d ",set[index]);
      }
      printf("}\n");
  }