Compilare: user.cpp: In function ‘void compute(int)’: user.cpp:39:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<g[node].size();i++){ ^ user.cpp: In function ‘int main()’: user.cpp:62:40: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] current[current_length]=NULL; ^ user.cpp:46:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lant.in","r",stdin); ^ user.cpp:47:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lant.out","w",stdout); ^ user.cpp:50:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&k); ^