View Compilation Error

0_0_24304839_21936.cpp: In function 'bool dfs(int)':
0_0_24304839_21936.cpp:20:6: error: 'f' was not declared in this scope
   if(f[t]) continue;
      ^
0_0_24304839_21936.cpp: In function 'int main()':
0_0_24304839_21936.cpp:36:10: error: 'f' was not declared in this scope
   memset(f, false, sizeof(f));
          ^