Compilare: user.cpp: In function ‘void quickSort(long long unsigned int*, long long unsigned int, long long unsigned int)’: user.cpp:14:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (arr[i] < pivot) ^ user.cpp:16:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (arr[j] > pivot) ^ user.cpp:28:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (left < j) ^ user.cpp:30:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i < right) ^ user.cpp: In function ‘int main()’: user.cpp:35:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cocochanel.in","r",stdin); ^ user.cpp:36:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cocochanel.out","w",stdout); ^ user.cpp:37:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%llu %llu",&n,&m); ^ user.cpp:38:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=1;i<=n;++i) scanf("%llu",&a[i]); ^ user.cpp:39:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=1;i<=m;++i) scanf("%llu",&b[i]); ^