Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:84:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (act.size() <= k) { ^ user.cpp:77:22: warning: unused variable ‘pos’ [-Wunused-variable] static int need, pos; ^ user.cpp: In function ‘bool check(long long int)’: user.cpp:126:12: warning: unused variable ‘pos’ [-Wunused-variable] int i, pos, need; ^ user.cpp:126:17: warning: unused variable ‘need’ [-Wunused-variable] int i, pos, need; ^ user.cpp: In function ‘int main()’: user.cpp:166:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("oneouts.out","w",stdout); ^ user.cpp: In constructor ‘Buffer::Buffer(std::string, int)’: user.cpp:22:46: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(name.c_str(), "r", stdin); ^ user.cpp: In member function ‘void Buffer::refill()’: user.cpp:55:43: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(&data[0], 1, dim, stdin); ^ user.cpp: In function ‘void pre()’: user.cpp:107:9: warning: ‘last’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (go[i] <= last) { ^