#include <bits/stdc++.h>
using namespace std;
struct DSU {
vector<int> p, sz;
DSU(int n) {
p.resize(n);
iota(p.begin(), p.end(), 0);
sz.assign(n, 1);
}
int root(int x) {
if (x == p[x]) {
return x;
}
return p[x] = root(p[x]);
}
bool connected(int u, int v) {
return root(u) == root(v);
}
bool unite(int u, int v) {
int x = root(u), y = root(v);
if (x == y) {
return false;
}
if (sz[y] < sz[x]) {
swap(x, y);
}
p[x] = y;
sz[y] += sz[x];
return true;
}
};
const int kN = 1e3;
vector<vector<int>> g;
bitset<kN> vis;
vector<int> comp;
void dfs(int u) {
vis[u] = true;
comp.emplace_back(u);
for (int v : g[u]) {
if (!vis[v]) {
dfs(v);
}
}
}
int construct(vector<vector<int>> p) {
int n = p.size();
DSU dsu(n);
vector<vector<int>> sol(n, vector<int>(n));
g.resize(n);
for (int i = 0; i < n; ++i) {
for (int j = 0; j < n; ++j) {
if (p[i][j] == 3) {
return 0;
}
if (p[i][j] == 1) {
sol[i][j] = sol[j][i] = 1;
dsu.unite(i, j);
}
if (p[i][j] == 2) {
g[i].emplace_back(j);
}
}
}
DSU cycles(n);
for (int i = 0; i < n; ++i) {
if (!vis[dsu.root(i)]) {
comp.clear();
dfs(i);
for (int &v : comp) {
v = dsu.root(v);
vis[v] = true;
}
sort(comp.begin(), comp.end());
comp.erase(unique(comp.begin(), comp.end()), comp.end());
int m = comp.size();
if (m == 2) {
return 0;
}
if (m == 1) {
continue;
}
for (int j = 0; j < m; ++j) {
int k = comp[(j + 1) % m];
sol[comp[j]][k] = sol[k][comp[j]] = 1;
cycles.unite(comp[j], k);
}
}
}
for (int i = 0; i < n; ++i) {
for (int j = 0; j < n; ++j) {
if (p[i][j] == 0 && (dsu.connected(i, j) || cycles.connected(i, j))) {
return 0;
}
}
}
build(sol);
return 1;
}
Compilation message
supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:105:3: error: 'build' was not declared in this scope
105 | build(sol);
| ^~~~~
