Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:18:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < L[in].size() && !ok; i ++) { ^ user.cpp:35:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < L[in].size(); i ++) { ^ user.cpp: In function ‘int main()’: user.cpp:48:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hamilton.in", "r", stdin); ^ user.cpp:49:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hamilton.out", "w", stdout); ^