http://www.geeksforgeeks.org/print-sums-subsets-given-set/

SubsetSum.cpp

#include<iostream>
#include<vector>
//using namespace std;

bool isPowerOf2 (long long x)
{
  /* First x in the below expression is for the case when x is 0 */
	return x && (!(x&(x-1)));
}

std::vector<long long> subsetSums(std::vector<int> set)
{
	long long total = 1<<set.size();	//total number of subsets = size of power set = 2^n
	std::vector<long long> sums(total, 0);
	sums[1] = set[0];
	//std::cout << sums[0] << std::endl;
	//std::cout << sums[1] << std::endl;
	int effectiveBits = 1, prevPowOf2 = 1;
	for (long long i = 2; i < total; ++i)
	{
		if (isPowerOf2(i))
		{
			++effectiveBits;
			prevPowOf2 *= 2;
		}
		//std::cout << "e = " << effectiveBits << "\tp = " << prevPowOf2 << std::endl;
		
		sums[i] = set[effectiveBits-1] + sums[i-prevPowOf2];
		//std::cout << sums[i] << "\n";
	}
	
	return sums;
}
 
// Driver code
int main()
{
	std::vector<int> set = {5, 4, 3};
 
	std::vector<long long> sumsOfAllSubsets = subsetSums(set);
	for (auto sum : sumsOfAllSubsets)
		std::cout << sum << "\n";
	return 0;
}