molecules.cpp: In function 'std::vector<int> find_subset(int, int, std::vector<int>)':
molecules.cpp:16:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if (sum > upp) sum -= w[a[j++]];
~~~~^~~~~
molecules.cpp:18:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if (low <= sum && sum <= upp) return vector<int>(a.begin() + j, a.begin() + i + 1);
~~~~^~~~~~
molecules.cpp:18:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if (low <= sum && sum <= upp) return vector<int>(a.begin() + j, a.begin() + i + 1);
~~~~^~~~~~