View Compilation Error

0_0_33209957_21321.cpp:1:2: error: 'vis' does not name a type
  vis[i] = 1;//标记。
  ^
0_0_33209957_21321.cpp:2:7: error: expected constructor, destructor, or type conversion before ';' token
  dfs();
       ^
0_0_33209957_21321.cpp:3:2: error: 'vis' does not name a type
  vis[i]=0;//撤除标记，寻找是否有新的满足条件的组合。//https://blog.csdn.net/u011428875/article/details/24918967
  ^