View Compilation Error

0_0_39431952_18942.cpp:108:1: error: 'vector' does not name a type
  108 | vector<int> tree[N];
      | ^~~~~~
0_0_39431952_18942.cpp: In function 'void dfs(int)':
0_0_39431952_18942.cpp:113:24: error: 'tree' was not declared in this scope; did you mean 'free'?
  113 |     for(int i = 0; i < tree[now].size(); i++){
      |                        ^~~~
      |                        free
0_0_39431952_18942.cpp: In function 'int main()':
0_0_39431952_18942.cpp:205:13: error: 'tree' was not declared in this scope; did you mean 'free'?
  205 |             tree[i].clear();
      |             ^~~~
      |             free
0_0_39431952_18942.cpp:209:13: error: 'tree' was not declared in this scope; did you mean 'free'?
  209 |             tree[tmp].push_back(i);
      |             ^~~~
      |             free