Compilare: main.cpp: In function 'void backtr(int, std::vector<int>, int, std::vector<int>)': main.cpp:16:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<p.size();i++) ~^~~~~~~~~ main.cpp:17:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=1+i;j<p.size();j++) ~^~~~~~~~~ main.cpp:26:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<p.size();i++) ~^~~~~~~~~