#include <bits/stdc++.h>
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("-O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("fast-math")
//#pragma GCC optimize("no-stack-protector")
#define F first
#define S second
#define sz(x) int(x.size())
#define pb push_back
#define N 100001
using namespace std;
int x[N], y[N], a[N][2], n, xr[N], yr[N];
set <int> tx[N * 4], ty[N * 4], alone;
set <pair <int, int> > tx_del[N * 4], ty_del[N * 4];
vector <pair <int, char> > psh[N * 4];
vector <pair <pair <int, int>, char> > psh_del[N * 4];
bool mk[N], mkr[N][2];
vector <pair <int, int> > g, gr;
void Push(int v, int tl, int tr)
{
while (sz(psh[v]) > 0)
{
pair <int, char> val = psh[v].back();
psh[v].pop_back();
if (val.S == 'a') tx[v].insert(val.F); else ty[v].insert(val.F);
if (tl != tr) {psh[v + v].pb(val); psh[v + v + 1].pb(val);}
}
}
void upd(int v, int tl, int tr, int l, int r, int val, bool f)
{
Push(v, tl, tr);
if (tl > tr || l > r || r < tl || tr < l) return;
if (l <= tl && tr <= r) {if (!f) psh[v].pb({val, 'a'}); else psh[v].pb({val, 'b'}); Push(v, tl, tr); return;}
int md = (tl + tr) >> 1;
upd(v + v, tl, md, l, r, val, f);
upd(v + v + 1, md + 1, tr, l, r, val, f);
}
void Push_del(int v, int tl, int tr)
{
while (sz(psh_del[v]) > 0)
{
pair <pair <int, int>, char> pt = psh_del[v].back();
psh_del[v].pop_back();
if (pt.S == 'a') tx_del[v].insert(pt.F); else if (pt.S == 'b') ty_del[v].insert(pt.F);
else if (pt.S == 'c') tx_del[v].erase(pt.F); else ty_del[v].erase(pt.F);
if (tl != tr) {psh_del[v + v].pb(pt); psh_del[v + v + 1].pb(pt); }
}
}
void upd_del(int v, int tl, int tr, int l, int r, pair <int, int> val, bool f)
{
Push_del(v, tl, tr);
if (tl > tr || l > r || r < tl || tr < l) return;
if (l <= tl && tr <= r) {if (!f) psh_del[v].pb({val, 'a'}); else psh_del[v].pb({val, 'b'}); Push_del(v, tl, tr); return;}
int md = (tl + tr) >> 1;
upd_del(v + v, tl, md, l, r, val, f);
upd_del(v + v + 1, md + 1, tr, l, r, val, f);
}
void upd_remove(int v, int tl, int tr, int l, int r, pair <int, int> val, bool f)
{
Push_del(v, tl, tr);
if (tl > tr || l > r || r < tl || tr < l) return;
if (l <= tl && tr <= r) {if (!f) psh_del[v].pb({val, 'c'}); else psh_del[v].pb({val, 'd'}); Push_del(v, tl, tr); return;}
int md = (tl + tr) >> 1;
upd_remove(v + v, tl, md, l, r, val, f);
upd_remove(v + v + 1, md + 1, tr, l, r, val, f);
}
bool good(int v, int tl, int tr, int pos, int l, int r, bool f)
{
Push(v, tl, tr);
if (tl == tr)
{
set <int> :: iterator it;
if (f)
{
it = ty[v].lower_bound(l);
return (it == ty[v].end() ? 1 : *it > r);
}
else
{
it = tx[v].lower_bound(l);
return (it == tx[v].end() ? 1 : *it > r);
}
}
else
{
int md = (tl + tr) >> 1;
if (pos <= md) return good(v + v, tl, md, pos, l, r, f);
return good(v + v + 1, md + 1, tr, pos, l, r, f);
}
}
int good_del(int v, int tl, int tr, int pos, int l, int r, bool f)
{
Push_del(v, tl, tr);
if (tl == tr)
{
set <pair <int, int> > :: iterator it;
if (f)
{
it = ty_del[v].lower_bound({l, -1e9});
if (it == ty_del[v].end() || (*it).F > r) return -1;
return (*it).S;
}
else
{
it = tx_del[v].lower_bound({l, -1e9});
if (it == tx_del[v].end() || (*it).F > r) return -1;
return (*it).S;
}
}
else
{
int md = (tl + tr) >> 1;
if (pos <= md) return good_del(v + v, tl, md, pos, l, r, f);
return good_del(v + v + 1, md + 1, tr, pos, l, r, f);
}
}
bool gd(int fr, int sc)
{
if (x[fr] == x[sc])
{
if (y[fr] > y[sc]) swap(fr, sc);
return good(1, 1, N - 1, x[fr], y[fr], y[sc], 0);
}
else
{
if (x[fr] > x[sc]) swap(fr, sc);
return good(1, 1, N - 1, y[fr], x[fr], x[sc], 1);
}
}
void add_remove(int fr, int sc, int nm)
{
if (!mk[fr] && !ad[fr]) {ad[fr] = 1; alone.insert(fr);}
if (!mk[sc] && !ad[sc]) {ad[sc] = 1; alone.insert(sc);}
if (x[fr] == x[sc])
{
if (y[fr] > y[sc]) swap(fr, sc);
upd_remove(1, 1, N, y[fr], y[sc], {x[fr], nm }, 1);
}
else
{
if (x[fr] > x[sc]) swap(fr, sc);
upd_remove(1, 1, N, x[fr], x[sc], {y[fr], nm }, 0);
}
}
void seacrh(int fr, int sc)
{
if (x[fr] == x[sc])
{
if (y[fr] > y[sc]) swap(fr, sc);
int pt = good_del(1, 1, N, x[fr], y[fr], y[sc], 0);
while (pt != -1)
{
add_remove(gr[pt].F, gr[pt].S, pt);
pt = good_del(1, 1, N, x[fr], y[fr], y[sc], 0);
}
}
else
{
if (x[fr] > x[sc]) swap(fr, sc);
int pt = good_del(1, 1, N, y[fr], x[fr], x[sc], 1);
while (pt != -1)
{
add_remove(gr[pt].F, gr[pt].S, pt);
pt = good_del(1, 1, N, y[fr], x[fr], x[sc], 1);
}
}
}
void add(int fr, int sc)
{
if (x[fr] == x[sc])
{
g.pb({fr, sc});
if (y[fr] > y[sc]) swap(fr, sc);
upd(1, 1, N - 1, y[fr], y[sc], x[fr], 1);
seacrh(fr, sc);
}
else
{
g.pb({fr, sc});
if (x[fr] > x[sc]) swap(fr, sc);
upd(1, 1, N - 1, x[fr], x[sc], y[fr], 0);
seacrh(fr, sc);
}
}
void clr(int x)
{
mk[x] = 1;
if (a[x][1] != -1) {if (!mk[a[x][1]] && !ad[a[x][1]]) {ad[a[x][1]] = 1; alone.insert(a[x][1]);} a[x][1] = a[a[x][1]][1] = -1;}
if (a[x][0] != -1) {if (!mk[a[x][0]] && !ad[a[x][0]]) {ad[a[x][0]] = 0; alone.insert(a[x][0]);} a[x][0] = a[a[x][0]][0] = -1;}
}
void fnd()
{
while (sz(alone) > 0)
{
int v = *alone.begin();
alone.erase(alone.begin());
if (mk[v]) continue;
if (a[v][1] != -1 && gd(v, a[v][1])) {add(v, a[v][1]); clr(a[v][1]); clr(v); continue;}
if (a[v][0] != -1 && gd(v, a[v][0])) {add(v, a[v][0]); clr(a[v][0]); clr(v); continue;}
cout << "NE" << endl;
exit(0);
}
for (int i = 0; i < n; i++)
{
if (mk[i]) continue;
g.pb({i, a[i][0]});
clr(a[i][0]);
clr(i);
}
}
void add_del(int fr, int sc)
{
if (x[fr] == x[sc])
{
if (mkr[fr][0]) return;
mkr[fr][0] = 1;
mkr[sc][0] = 1;
if (y[fr] > y[sc]) swap(fr, sc);
upd_del(1, 1, N, y[fr], y[sc], {x[fr], sz(gr) }, 1);
gr.pb({fr, sc});
}
else
{
if (mkr[fr][1]) return;
mkr[fr][1] = 1;
mkr[sc][1] = 1;
if (x[fr] > x[sc]) swap(fr, sc);
upd_del(1, 1, N, x[fr], x[sc], {y[fr], sz(gr) }, 0);
gr.pb({fr, sc});
}
}
int main()
{
ios_base::sync_with_stdio(0); istream::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n;
for (int i = 1; i < N; i++) xr[i] = yr[i] = -1;
for (int i = 0; i < n; i++) {cin >> x[i] >> y[i]; a[i][0] = a[i][1] = -1;}
for (int i = 0; i < n; i++)
{
int X = x[i], Y = y[i];
if (xr[X] == -1) xr[X] = i; else {a[i][0] = xr[X]; a[xr[X]][0] = i;}
if (yr[Y] == -1) yr[Y] = i; else {a[i][1] = yr[Y]; a[yr[Y]][1] = i;}
}
for (int i = 0; i < n; i++)
{
if (a[i][0] == a[i][1] && a[i][1] == -1) {cout << "NE" << endl; exit(0);}
if (a[i][0] == -1 || a[i][1] == -1) alone.insert(i); else {add_del(i, a[i][0]); add_del(i, a[i][1]);}
}
fnd();
if (sz(g) != n / 2) {cout << "NE" << endl; exit(0);}
cout << "DA" << endl;
for (auto it : g) cout << it.F + 1 << " " << it.S + 1 << endl;
}
Compilation message
matching.cpp: In function 'void add_remove(int, int, int)':
matching.cpp:189:21: error: 'ad' was not declared in this scope
if (!mk[fr] && !ad[fr]) {ad[fr] = 1; alone.insert(fr);}
^~
matching.cpp:189:21: note: suggested alternative: 'gd'
if (!mk[fr] && !ad[fr]) {ad[fr] = 1; alone.insert(fr);}
^~
gd
matching.cpp:191:21: error: 'ad' was not declared in this scope
if (!mk[sc] && !ad[sc]) {ad[sc] = 1; alone.insert(sc);}
^~
matching.cpp:191:21: note: suggested alternative: 'gd'
if (!mk[sc] && !ad[sc]) {ad[sc] = 1; alone.insert(sc);}
^~
gd
matching.cpp: In function 'void clr(int)':
matching.cpp:265:46: error: 'ad' was not declared in this scope
if (a[x][1] != -1) {if (!mk[a[x][1]] && !ad[a[x][1]]) {ad[a[x][1]] = 1; alone.insert(a[x][1]);} a[x][1] = a[a[x][1]][1] = -1;}
^~
matching.cpp:265:46: note: suggested alternative: 'add'
if (a[x][1] != -1) {if (!mk[a[x][1]] && !ad[a[x][1]]) {ad[a[x][1]] = 1; alone.insert(a[x][1]);} a[x][1] = a[a[x][1]][1] = -1;}
^~
add
matching.cpp:267:46: error: 'ad' was not declared in this scope
if (a[x][0] != -1) {if (!mk[a[x][0]] && !ad[a[x][0]]) {ad[a[x][0]] = 0; alone.insert(a[x][0]);} a[x][0] = a[a[x][0]][0] = -1;}
^~
matching.cpp:267:46: note: suggested alternative: 'add'
if (a[x][0] != -1) {if (!mk[a[x][0]] && !ad[a[x][0]]) {ad[a[x][0]] = 0; alone.insert(a[x][0]);} a[x][0] = a[a[x][0]][0] = -1;}
^~
add
