supertrees.cpp:11:11: error: expected identifier before '(' token
11 | void union(int u, int v){
| ^
supertrees.cpp:11:12: error: expected unqualified-id before 'int'
11 | void union(int u, int v){
| ^~~
supertrees.cpp:11:12: error: expected ')' before 'int'
11 | void union(int u, int v){
| ~^~~
| )
supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:22:9: error: expected primary-expression before 'union'
22 | union(i, j);
| ^~~~~
supertrees.cpp:23:9: error: 'adj' was not declared in this scope
23 | adj[i][j] = adj[j][i] = 1;
| ^~~