#include "parks.h"
#include <bits/stdc++.h>
#define SIZE 200001
using namespace std;
struct point
{
int x, y, idx;
};
set<pair<int, int> > vis;
map<pair<int, int>, int> fnt;
point p[SIZE];
int root[SIZE], cnt;
int dx[5][3]=
{
{ 1, 1 },
{ 1, -1 },
{ -1, 1 },
{ -1, -1 }
};
int Find(int x)
{
if (x==root[x]) return x;
return root[x]=Find(root[x]);
}
void Union(int x, int y)
{
if (Find(x)==Find(y)) return;
root[root[y]]=root[x], cnt++;
}
bool comp1(point a, point b)
{
if (a.x==b.x) return a.y<b.y;
return a.x<b.x;
}
bool comp2(point a, point b)
{
if (a.y==b.y) return a.x<b.x;
return a.y<b.y;
}
int construct_roads(vector<int> X, vector<int> Y)
{
int N=X.size();
for (int i=0; i<N; i++) {
p[i].x=X[i], p[i].y=Y[i], p[i].idx=i, root[i]=i;
fnt.insert({{X[i], Y[i]}, i});
}
sort(p, p+N, comp1);
for (int i=0; i<N-1; i++) if (p[i].x==p[i+1].x && p[i].y==p[i+1].y-2) Union(p[i].idx, p[i+1].idx);
sort(p, p+N, comp2);
for (int i=0; i<N-1; i++) if (p[i].y==p[i+1].y && p[i].x==p[i+1].x-2) Union(p[i].idx, p[i+1].idx);
if (cnt!=N-1) return 0;
int bx, by;
vector<int> u, v, a, b;
for (int i=0; i<N; i++) for (int j=0; j<4; j++) {
bx=p[i].x+dx[j][0], by=p[i].y+dx[j][1];
if (vis.find({bx, by})==vis.end()) {
vis.insert({bx, by});
if ((bx+by)%4==0) {
if (fnt.find({bx-1, by-1})!=fnt.end() && fnt.find({bx-1, by+1})!=fnt.end()) u.push_back(fnt[{bx-1, by-1}]), v.push_back(fnt[{bx-1, by+1}]), a.push_back(bx), b.push_back(by);
else if (fnt.find({bx+1, by-1})!=fnt.end() && fnt.find({bx+1, by+1})!=fnt.end()) u.push_back(fnt[{bx+1, by-1}]), v.push_back(fnt[{bx+1, by+1}]), a.push_back(bx), b.push_back(by);
}
else {
if (fnt.find({bx-1, by-1})!=fnt.end() && fnt.find({bx+1, by-1})!=fnt.end()) u.push_back(fnt[{bx-1, by-1}]), v.push_back(fnt[{bx+1, by-1}]), a.push_back(bx), b.push_back(by);
else if (fnt.find({bx-1, by+1})!=fnt.end() && fnt.find({bx+1, by+1})!=fnt.end()) u.push_back(fnt[{bx-1, by+1}]), v.push_back(fnt[{bx+1, by+1}]), a.push_back(bx), b.push_back(by);
}
}
}
build(u, v, a, b);
return 1;
}
