Question

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How to find all possible subsets of a given array?

How can all ways of selection of items be generated efficiently using C++?

For example, if there are there items A, B and C.

[A,B,C] => [A], [B], [C], [A,B], [B,C], [A,C], [A, B, C]

Answer 1

For that input set:

#include <iostream>

void print(int b, char *a, int n)
{
   for(int i = 0 ; i < n ; i++)
   {
     if( b & 0x1)  std::cout << a[i];
     b = b >> 1;
   }
   std::cout << std::endl; 
}

int main() {
        char a[] = {'A','B','C'};
        for(int i = 1 ; i < 8 ; i++ )
            print(i,a,3);
        return 0;
}

Output:

A
B
AB
C
AC
BC
ABC

Demo : http://ideone.com/2Wxbi

Now it’s your turn to improve and generalize this approach, and find it’s limitations.