Compilare: user.cpp: In function ‘int main()’: user.cpp:22:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (unsigned int i = 0; i < n; ++i) { ^ user.cpp:30:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (unsigned int i = 0; i < n; ++i) { ^ user.cpp: In function ‘bool checkPerm(std::vector<int>)’: user.cpp:44:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (unsigned int i = 0; i < n; ++i) { ^ user.cpp:45:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (a[i] != i+1) { ^