molecules.cpp: In function 'std::vector<int> find_subset(int, int, std::vector<int>)':
molecules.cpp:23:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(i=0; i<w.size(); ++i) W.push_back({w[i], i});
              ~^~~~~~~~~
molecules.cpp:27:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(i=0; i<W.size(); ++i)
              ~^~~~~~~~~
molecules.cpp:34:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(j<S.size() && S[j] < L) ++j;
           ~^~~~~~~~~
molecules.cpp:35:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(j<S.size() && S[j] <= R)
        ~^~~~~~~~~
molecules.cpp:38:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(i=0; i<S.size(); ++i)
              ~^~~~~~~~~
molecules.cpp:40:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while(j<S.size() && S[j] - S[i] < L) ++j;
               ~^~~~~~~~~
molecules.cpp:41:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(j<S.size() && S[j] - S[i] <= R) return solution(i+1, j);
            ~^~~~~~~~~