Compilare: user.cpp: In function ‘void dijkstra()’: user.cpp:138:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<G[v].size(); ++i){ ^ user.cpp:141:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(P[u] != -1){ ^ user.cpp: In function ‘int main()’: user.cpp:184:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<G[s].size(); ++i) ^ user.cpp:168:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.in", "r", stdin); ^ user.cpp:170:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.out", "w", stdout); ^ user.cpp:172:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:177:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &from, &to, &cost); ^