#include<bits/stdc++.h>
//#include "supertrees.h"
using namespace std;
#define all(v) v.begin(), v.end()
typedef long long ll;
const int NMAX = 1005;
int par[NMAX], vis[NMAX], p[NMAX][NMAX], a, b;
vector<int> C[NMAX], V, t;
int find(int x){return par[x] == -1 ? x : par[x] = find(par[x]);}
void dfs(int x){
if(vis[x]) return;
vis[x] = 1;
t.emplace_back(x);
for(int& y : V) if(!vis[y] && p[x][y] == 2) dfs(y);
return;
}
int construct(vector<vector<int>>p_){
int n = p_.size(), a, b;
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) p[i][j] = p_[i][j];
vector<vector<int>> E(n, vector<int>(n, 0));
memset(par, -1, sizeof(par));
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++){
if(p[i][j] == 3) return 0;
a = find(i); b = find(j);
if(a == b) continue;
if(p[i][j] == 1){
par[b] = a; E[i][j] = 1;
}
}
for(int i = 0; i < n; i++) C[find(i)].emplace_back(i);
for(int i = 0; i < n; i++)
if(find(i) == i){
V.emplace_back(i);
for(int&x : C[i])
for(int j = 0; j < n; j++)
if(p[x][j] != p[i][j]) return 0;
}
for(int& x : V)
if(!vis[x]){
t.clear();
dfs(x);
int sz = t.size();
if(sz == 1) continue;
for(int i = 0; i < sz; i++){
a = t[i], b = t[(i + 1) % sz];
E[a][b] = E[b][a] = 1;
for(int j = 0; j < sz; j++)
if(i != j && p[t[i]][t[j]] != 2) return 0;
}
}
build(E);
return 1;
}
/*
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n;
cin >> n;
vector<vector<int>> v (n, vector<int>(n, 0));
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) cin >> v[i][j];
cout << construct(v) << '\n';
return 0;
}
*/
/*
4
1 1 2 2
1 1 2 2
2 2 1 2
2 2 2 1
2
1 0
0 1
2
1 3
3 1
*/
Compilation message
supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:63:5: error: 'build' was not declared in this scope
63 | build(E);
| ^~~~~
