Compilare: main.cpp: In function 'void solve2()': main.cpp:21:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); ++i) { ~~^~~~~~~~~~ main.cpp:25:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(zero == s.size() || (one == 1 && s[s.size() - 1] == '1')) { ~~~~~^~~~~~~~~~~ main.cpp:32:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = i + 2; j < s.size(); ++j) { ~~^~~~~~~~~~ main.cpp:40:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(one == s.size()) { ~~~~^~~~~~~~~~~ main.cpp:54:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = i + 1; j < s.size(); ++j) { ~~^~~~~~~~~~