Compilare: user.cpp: In function ‘int down(int)’: user.cpp:37:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int up(int)’: user.cpp:46:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int del(int)’: user.cpp:53:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:77:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<=v[mn].size()-1;i++) ^ user.cpp:57:37: 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:58:39: 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:59:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:62:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&x,&y,&z); ^