View Compilation Error

0_0_21657314_28124.cpp:22:1: error: 'vector' does not name a type
 vector<ll> g[N];
 ^
0_0_21657314_28124.cpp: In function 'void dfs(ll)':
0_0_21657314_28124.cpp:39:18: error: 'g' was not declared in this scope
     for(ll i=0;i<g[u].size();i++)
                  ^
0_0_21657314_28124.cpp: In function 'int main()':
0_0_21657314_28124.cpp:102:13: error: 'g' was not declared in this scope
             g[i].clear();
             ^
0_0_21657314_28124.cpp:107:13: error: 'g' was not declared in this scope
             g[u].push_back(v);
             ^