View Compilation Error

0_0_20757868_21447.cpp: In function 'void dfs(int)':
0_0_20757868_21447.cpp:12:25: error: 'f' was not declared in this scope
     if (a[u].size()==0) f[u][1<<v[u]]=1;
                         ^
0_0_20757868_21447.cpp:16:9: error: 'f' was not declared in this scope
         f[u][1<<v[*it]]=f[*it][dfs(*it);
         ^
0_0_20757868_21447.cpp:16:40: error: expected ']' before ';' token
         f[u][1<<v[*it]]=f[*it][dfs(*it);
                                        ^
0_0_20757868_21447.cpp: In function 'int main()':
0_0_20757868_21447.cpp:23:11: error: request for member 'clear' in 'a', which is of non-class type 'std::vector<int> [50010]'
         a.clear();
           ^