Compilare: user.cpp: In member function ‘void Tree::dfs(int)’: user.cpp:67:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i > d.size()) exit(0); ~~^~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:91:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:96:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &val[i]); ^ user.cpp:103:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &u); ^