Compilare: user.cpp: In function ‘int main()’: user.cpp:61:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("something.in", "r", stdin); ^ user.cpp:62:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("something.out", "w", stdout); ^ user.cpp:67:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &xx, &yy); ^ user.cpp:65:5: warning: ‘m’ is used uninitialized in this function [-Wuninitialized] for (int i = 1; i <= m; ++i) { ^ user.cpp: In function ‘void dfs(int, int)’: user.cpp:14:17: warning: ‘son’ may be used uninitialized in this function [-Wmaybe-uninitialized] sol[nod] = c; ^ user.cpp: In function ‘int main()’: user.cpp:72:5: warning: ‘n’ is used uninitialized in this function [-Wuninitialized] if (n < 3) { ^