friend.cpp: In function 'int findSample(int, int*, int*, int*)':
friend.cpp:13:3: error: 'stack' was not declared in this scope
13 | stack<pair<int,pair<int,int>>> s;
| ^~~~~
friend.cpp:13:9: error: 'pair' was not declared in this scope
13 | stack<pair<int,pair<int,int>>> s;
| ^~~~
friend.cpp:13:14: error: expected primary-expression before 'int'
13 | stack<pair<int,pair<int,int>>> s;
| ^~~
friend.cpp:14:3: error: 'vector' was not declared in this scope
14 | vector<bool> vis(n);
| ^~~~~~
friend.cpp:14:10: error: expected primary-expression before 'bool'
14 | vector<bool> vis(n);
| ^~~~
friend.cpp:15:10: error: expected primary-expression before 'int'
15 | vector<int> col(n);
| ^~~
friend.cpp:16:3: error: 's' was not declared in this scope
16 | s.push({0,0,-1});
| ^
friend.cpp:18:9: error: expected primary-expression before 'int'
18 | pair<int,int> a = s.top();
| ^~~
friend.cpp:20:15: error: 'a' was not declared in this scope
20 | int node = a.first;
| ^
friend.cpp:23:4: error: 'col' was not declared in this scope
23 | col[node] = flag;
| ^~~
friend.cpp:24:4: error: 'vis' was not declared in this scope
24 | vis[node] = true;
| ^~~
friend.cpp:25:18: error: 'adj' was not declared in this scope
25 | for (auto u : adj[node]){
| ^~~
friend.cpp:33:8: error: 'col' was not declared in this scope
33 | if (col[i] == 0){
| ^~~
friend.cpp:40:10: error: 'max' was not declared in this scope
40 | return max(one,zero);
| ^~~
friend.cpp:42:9: error: 'ans' was not declared in this scope
42 | return ans;
| ^~~