Compilare: user.cpp: In function ‘int Union(int, int)’: user.cpp:70:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘void kruskal(int, int)’: user.cpp:129:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( i = 0 ; i < min_span.size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:180:9: warning: unused variable ‘i’ [-Wunused-variable] int i; ^ user.cpp: In function ‘void read_data(int&, int&)’: user.cpp:35:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:39:59: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&temp.node1,&temp.node2,&temp.cost); ^ user.cpp: In function ‘void kruskal(int, int)’: user.cpp:116:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&k); ^ user.cpp:125:59: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&temp.node1,&temp.node2,&temp.cost); ^ user.cpp: In function ‘int main()’: user.cpp:182:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("online.in","r",stdin); ^ user.cpp:183:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("online.out","w",stdout); ^