Compilare: main.cpp:1:0: warning: ignoring #pragma optimize [-Wunknown-pragmas] #pragma optimize ("unroll-loops") main.cpp: In function 'std::vector<int> sort(std::vector<int>&)': main.cpp:16:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < head.size(); i++){ ~~^~~~~~~~~~~~~ main.cpp:21:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size(); i++){ ~~^~~~~~~~~~ main.cpp: In function 'void solve(int, std::vector<int>&, std::vector<int>&, std::vector<int>&)': main.cpp:39:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(pos_use < use.size() and A[use[pos_use]] <= i){ ~~~~~~~~^~~~~~~~~~~~ main.cpp:44:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(pos_take < take.size() and B[take[pos_take]] <= i){ ~~~~~~~~~^~~~~~~~~~~~~ main.cpp: In function 'void setIO(std::__cxx11::string, bool, bool)': main.cpp:8:51: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] if(input) freopen(inputname.c_str(), "r", stdin); ^ main.cpp:9:54: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] if(output) freopen(outputname.c_str(), "w", stdout); ^ main.cpp: In function 'int main()': main.cpp:62:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ main.cpp:64:41: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &A[0], &B[0], &C[0]); ^