Compilare: user.cpp: In function ‘bool valid()’: user.cpp:35:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘void solve()’: user.cpp:113:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < A.size(); i++) ^ user.cpp:117:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < B.size(); i++) ^ user.cpp:120:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < in.size(); i++) { ^ user.cpp:128:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < in.size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:160:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("magnet.in","r",stdin); ^ user.cpp:161:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("magnet.out","w",stdout); ^ user.cpp:163:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ user.cpp:165:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:172:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &A[i]); ^ user.cpp:175:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &B[i]); ^ user.cpp: In function ‘void give_sol()’: user.cpp:94:21: warning: ‘before’ may be used uninitialized in this function [-Wmaybe-uninitialized] sum[0] += before; ^