// 我的心裡只有你沒有他
#include "parks.h"
#include <bits/stdc++.h>
// #define int ll
using namespace std;
#define ll long long
#define y1 zck_is_king
#define pii pair<ll, ll>
#define ull unsigned ll
#define f first
#define s second
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define SQ(x) (x)*(x)
#define MN(a,b) a = min(a,(__typeof__(a))(b))
#define MX(a,b) a = max(a,(__typeof__(a))(b))
#define pb push_back
#define REP(i,n) for (int i = 0; i<n; ++i)
#define RREP(i,n) for (int i = n-1; i>=0; --i)
#define REP1(i,n) for (int i = 1; i<=n; ++i)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#ifdef BALBIT
#define IOS()
#define bug(...) fprintf(stderr,"#%d (%s) = ",__LINE__,#__VA_ARGS__),_do(__VA_ARGS__);
template<typename T> void _do(T &&x){cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T &&x, S &&...y){cerr<<x<<", ";_do(y...);}
#else
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0);
#define endl '\n'
#define bug(...)
#endif
const int maxn = 4e5+5;
vector<int> rU,rV,rA,rB;
set<pii> used; // benches in use
map<pii, int> id;
void ADD(int u, int v, int a, int b) {
rU.pb(u);
rV.pb(v);
rA.pb(a);
rB.pb(b);
used.insert({a,b});
}
int GET(int x, int y){
return id.count({x,y})?id[{x,y}]:-1;
}
int dx[] = {1,0,-1,0};
int dy[] = {0,1,0,-1};
bool seen[maxn];
vector<int> X, Y;
void dfs(int v, int sd) { //sd: starting direction
seen[v]= 1;
int x = X[v], y = Y[v];
for (int df = 0; df < 4; ++df) {
int d = (df + sd) % 4;
int tx = x + dx[d]*2, ty = y + dy[d]*2;
int u = GET(tx,ty);
if (u == -1 || seen[u]) continue;
int pd = (d-1+4)%4;
int nxtd = (d+1)%4;
int b1x = x + dx[d] + dx[pd], b1y = y + dy[d] + dy[pd];
int b2x = x + dx[d] + dx[nxtd], b2y = y + dy[d] + dy[nxtd];
bug(v,u,d);
bug(b1x,b1y);
bug(b2x,b2y);
if (!used.count({b1x, b1y})) {
ADD(u,v,b1x,b1y);
}else{
continue;
assert(!used.count({b2x,b2y}));
ADD(u,v,b2x,b2y);
}
dfs(u, pd);
}
}
int construct_roads(std::vector<int> _x, std::vector<int> _y) {
X = _x, Y = _y;
int n = SZ(X);
REP(i,n) {
id[{X[i], Y[i]}] = i;
}
dfs(0, 0);
if (SZ(rU) < n-1) return 0;
build(rU,rV,rA,rB);
return 1;
}
/*
4, 4, 6, 4, 2], [4, 6, 4, 2, 4
5
4 4
4 6
6 4
4 2
2 4
25
-4 4
0 0
0 2
0 4
0 6
0 8
-2 0
-2 2
-2 4
-2 6
-2 8
-4 0
-4 2
-4 6
-4 8
-6 0
-6 2
-6 4
-6 6
-6 8
-8 0
-8 2
-8 4
-8 6
-8 8
*/
