#include <bits/stdc++.h>
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
//#pragma GCC optimize("no-stack-protector,fast-math")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<(x)<<endl;
#define debugp(x) cerr<<#x<<"= {"<<(x.first)<<", "<<(x.second)<<"}"<<endl;
#define debug2(x, y) cerr<<"{"<<#x<<", "<<#y<<"} = {"<<(x)<<", "<<(y)<<"}"<<endl;
#define debugv(v) {cerr<<#v<<" : ";for (auto x:v) cerr<<x<<' ';cerr<<endl;}
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;
const ld eps=1e-7;
const int inf=1000000010;
const ll INF=10000000000000010LL;
const int mod = 1000000007;
const int MAXN = 100010, SQ=320, CNT=MAXN/SQ+1;
inline void erase(vector<int> &vec, int x){
if (vec.back()!=x) swap(vec[0], vec[1]);
vec.pop_back();
}
int n, m, k, u, v, x, y, t, a, b;
int X[MAXN], Y[MAXN];
bool mark[MAXN];
vector<int> G[MAXN], vx[MAXN], vy[MAXN];
vector<pii> ans;
queue<int> Q;
inline bool bad(int a, int b, int c, int d){
bool t1=(X[a]==X[b]), t2=(X[c]==X[d]);
if (t1==t2) return 0;
if (t1){
swap(a, c);
swap(b, d);
}
if (X[c]<X[a] || X[b]<X[c]) return 0;
if (Y[c]>Y[d]) swap(c, d);
return (Y[c]<=Y[a] && Y[a]<=Y[d]);
}
inline void disjoint(int u, int v){
erase(G[u], v);
erase(G[v], u);
}
struct SQRT{
vector<int> vec[MAXN];
int L[MAXN], R[MAXN];
pii block[CNT][SQ]; // {L, pos}
pii mx[CNT][SQ]; // {R, pos}
void rebuild(int id){
for (int i=0; i<SQ; i++) block[id][i]={L[SQ*id+i], SQ*id+i};
sort(block[id], block[id]+SQ);
for (int i=0; i<SQ; i++) mx[id][i]={R[block[id][i].second], block[id][i].second};
for (int i=1; i<SQ; i++) mx[id][i]=max(mx[id][i], mx[id][i-1]);
}
void Draw(int l, int r, int h){
if (l>r) swap(l, r);
int idl=l/SQ, idr=r/SQ;
while (l<r){
//debug(l)
//debug2(L[l], R[l])
if (l%SQ==0 && l+SQ<=r){
int id=l/SQ;
while (1){
int tmp=lower_bound(block[id], block[id]+SQ, pii(h, 0))-block[id]-1;
if (tmp==-1 || mx[id][tmp].first<h) break ;
int pos=mx[id][tmp].second;
disjoint(vec[pos][0], vec[pos][1]);
L[pos]=R[pos]=0;
rebuild(id);
}
l+=SQ;
}
else{
if (L[l]<h && h<R[l]) disjoint(vec[l][0], vec[l][1]);
l++;
}
}
rebuild(idl);
rebuild(idr);
}
} SQX, SQY;
int main(){
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
cin>>n;
for (int i=1; i<=n; i++){
cin>>X[i]>>Y[i];
if (vx[X[i]].size()){
int j=vx[X[i]][0];
if (Y[i]==Y[j]){
mark[i]=mark[j]=1;
ans.pb({j, i});
continue ;
}
G[i].pb(j);
G[j].pb(i);
}
if (vy[Y[i]].size()){
int j=vy[Y[i]][0];
G[i].pb(j);
G[j].pb(i);
}
vx[X[i]].pb(i);
vy[Y[i]].pb(i);
}
for (int i=0; i<MAXN; i++){
if (vx[i].size()==2 && Y[vx[i][0]]>Y[vx[i][1]]) swap(vx[i][0], vx[i][1]);
if (vy[i].size()==2 && X[vy[i][0]]>X[vy[i][1]]) swap(vy[i][0], vy[i][1]);
SQX.vec[i]=vx[i];
SQY.vec[i]=vy[i];
}
//debugv(vx[2])
for (int i=0; i<MAXN; i++) if (vx[i].size()==2) SQX.L[i]=Y[vx[i][0]], SQX.R[i]=Y[vx[i][1]];
for (int i=0; i<MAXN; i++) if (vy[i].size()==2) SQY.L[i]=X[vy[i][0]], SQY.R[i]=X[vy[i][1]];
for (int i=0; i<CNT; i++) SQX.rebuild(i), SQY.rebuild(i);
/*
SQX.Draw(1, 3, 2);
debugv(G[3])
return 0;
*/
for (int i=1; i<=n; i++) if (G[i].size()<2) Q.push(i);
while (Q.size()){
int v=Q.front();
Q.pop();
if (mark[v]) continue ;
if (G[v].size()==0) kill("NE")
int u=G[v][0];
mark[v]=mark[u]=1;
ans.pb({u, v});
//debug2(u, v)
for (int i:G[u]) if (i!=v){
erase(G[i], u);
Q.push(i);
}
if (Y[u]==Y[v]) SQX.Draw(X[u], X[v], Y[u]);
else SQY.Draw(Y[u], Y[v], X[u]);
}
for (int i=1; i<=n; i++) if (!mark[i]){
int j=G[i][0];
if (X[i]!=X[j]) j=G[i][1];
ans.pb({i, j});
mark[i]=mark[j]=1;
}
cout<<"DA\n";
for (pii p:ans) cout<<p.first<<' '<<p.second<<'\n';
return 0;
}
/*
4
10 20
30 20
20 30
20 10
*/
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
22 ms |
15352 KB |
Output is correct |
| 2 |
Correct |
20 ms |
15352 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
22 ms |
15352 KB |
Output is correct |
| 2 |
Correct |
20 ms |
15352 KB |
Output is correct |
| 3 |
Correct |
20 ms |
15352 KB |
Output is correct |
| 4 |
Correct |
20 ms |
15356 KB |
Output is correct |
| 5 |
Correct |
19 ms |
15352 KB |
Output is correct |
| 6 |
Incorrect |
20 ms |
15352 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
22 ms |
15352 KB |
Output is correct |
| 2 |
Correct |
20 ms |
15352 KB |
Output is correct |
| 3 |
Correct |
20 ms |
15352 KB |
Output is correct |
| 4 |
Correct |
20 ms |
15356 KB |
Output is correct |
| 5 |
Correct |
19 ms |
15352 KB |
Output is correct |
| 6 |
Incorrect |
20 ms |
15352 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
22 ms |
15352 KB |
Output is correct |
| 2 |
Correct |
20 ms |
15352 KB |
Output is correct |
| 3 |
Correct |
20 ms |
15352 KB |
Output is correct |
| 4 |
Correct |
20 ms |
15356 KB |
Output is correct |
| 5 |
Correct |
19 ms |
15352 KB |
Output is correct |
| 6 |
Incorrect |
20 ms |
15352 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
22 ms |
15352 KB |
Output is correct |
| 2 |
Correct |
20 ms |
15352 KB |
Output is correct |
| 3 |
Correct |
20 ms |
15352 KB |
Output is correct |
| 4 |
Correct |
20 ms |
15356 KB |
Output is correct |
| 5 |
Correct |
19 ms |
15352 KB |
Output is correct |
| 6 |
Incorrect |
20 ms |
15352 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
