Compilare: user.cpp: In function ‘int BellmanFord(int)’: user.cpp:30:27: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] predecessor[node] = NULL; ^ user.cpp: In function ‘int main()’: user.cpp:69:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.in", "r", stdin); ^ user.cpp:70:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.out", "w", stdout); ^ user.cpp:72:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &vertices, &edges); ^ user.cpp:75:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &u, &v, &weight); ^