Compilare: user.cpp: In function ‘void dfs(int, int, int)’: user.cpp:15:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < g[n].size(); i++) ~~^~~~~~~~~~~~~ user.cpp: In function ‘int dfs2(int)’: user.cpp:26:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < g[n].size(); i++) ~~^~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:38:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("petrica.in", "r", stdin); ^ user.cpp:39:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("petrica.out", "w", stdout); ^ user.cpp:40:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:42:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &p[i]); ^ user.cpp:46:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^ user.cpp:88:29: warning: ‘gr’ may be used uninitialized in this function [-Wmaybe-uninitialized] val[gr] -= val[l + 1]; ~~~~~~~~^~~~~~~~~~~~~