#include "parks.h"
#include <bits/stdc++.h>
using namespace std;
struct DSU {
vector<int> e;
DSU (int n) {
e = vector<int>(n, -1);
}
int get(int x) {
return e[x] < 0 ? x : e[x] = get(e[x]);
}
int size(int x) {
return -e[get(x)];
}
bool unite(int x, int y) {
x = get(x);
y = get(y);
if (x == y) return false;
if (e[x] > e[y]) swap(x, y);
e[x] += e[y];
e[y] = x;
return true;
}
};
int construct_roads(std::vector<int> x, std::vector<int> y) {
int N = x.size();
const int MAXN = 2e5;
vector<map<int, int>> mp(MAXN + 10);
for (int i = 0; i < N; ++i) {
mp[x[i]][y[i]] = i;
}
vector<array<int, 4>> edges;
DSU dsu(N);
for (int i = 0; i < N; ++i) {
if (mp[x[i]].count(y[i] + 2)) {
dsu.unite(i, mp[x[i]][y[i] + 2]);
int j = mp[x[i]][y[i] + 2];
int ny = y[i] + 1;
int nx;
if (((x[i] + y[i]) / 2) & 1) {
nx = x[i] - 1;
} else {
nx = x[i] + 1;
}
edges.push_back({nx, ny, i, j});
}
if (mp[x[i] + 2].count(y[i])) {
dsu.unite(i, mp[x[i] + 2][y[i]]);
int j = mp[x[i] + 2][y[i]];
int ny;
int nx = x[i] + 1;
if (((x[i] + y[i]) / 2) & 1) {
ny = y[i] + 1;
} else {
ny = y[i] - 1;
}
edges.push_back({nx, ny, i, j});
}
}
if (dsu.size(0) != N) return 0;
sort(begin(edges), end(edges));
vector<int> u, v, a, b;
for (int it = 0; it < (int)edges.size(); ++it) {
int i = edges[it][2];
int j = edges[it][3];
int x = edges[it][0];
int y = edges[it][1];
if (it > 0 && x == edges[it - 1][0] && y == edges[it - 1][1]) continue;
u.push_back(i);
v.push_back(j);
a.push_back(x);
b.push_back(y);
}
build(u, v, a, b);
return 1;
}
