#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
#define F first
#define S second
#define sz(x) int(x.size())
#define pb push_back
#define N 100005
#define M ll(998244353)
using namespace std;
//using namespace __gnu_pbds;
typedef long double ld;
typedef long long ll;
typedef short int si;
//typedef tree<int, null_type, less <int>, rb_tree_tag, tree_order_statistics_node_update> oredered_set;
int x[N], y[N], a[N][2], n;
bool mk[N];
queue <pair <int, int> > qr;
vector <pair <int, int> > vert, gorz;
bool gd(int fr, int sc)
{
if (x[fr] == x[sc])
{
if (y[fr] > y[sc]) swap(fr, sc);
for (auto it : vert)
{
int _fr = it.F, _sc = it.S;
if (x[_fr] > x[_sc]) swap(_fr, _sc);
if (y[_fr] < y[fr] || y[sc] < y[_fr]) continue;
if (x[fr] < x[_fr] || x[_sc] < x[fr]) continue;
return 0;
}
}
else
{
if (x[fr] > x[sc]) swap(fr, sc);
for (auto it : gorz)
{
int _fr = it.F, _sc = it.S;
if (y[_fr] > y[_sc]) swap(_fr, _sc);
if (x[_fr] < x[fr] || x[sc] < x[_fr]) continue;
if (y[fr] < y[_fr] || y[_sc] < y[fr]) continue;
return 0;
}
}
return 1;
}
void clr(int x)
{
mk[x] = 1;
if (a[x][1] != -1) a[x][1] = a[a[x][1]][1] = -1;
if (a[x][0] != -1) a[x][0] = a[a[x][0]][0] = -1;
}
void fnd()
{
for (int i = 0; i < n; i++)
{
if (mk[i]) continue;
if (a[i][1] == -1 && a[i][0] == -1) continue;
if (a[i][1] != -1 && a[i][0] != -1) continue;
if (a[i][1] != -1) {qr.push({a[i][1], a[a[i][1]][1]}); clr(a[i][1]); clr(i); return;}
if (a[i][0] != -1) {qr.push({a[i][0], a[a[i][0]][0]}); clr(a[i][0]); clr(i); return;}
}
for (int i = 0; i < n; i++)
{
if (mk[i]) continue;
if (a[i][1] == -1 && a[i][0] == -1) continue;
if (gd(i, a[i][0]) && gd(i, a[i][1])) continue;
if (!gd(i, a[i][0] && !gd(i, a[i][1]))) continue;
if (gd(i, a[i][0]))
{
qr.push({i, a[i][0]});
clr(a[i][0]);
clr(i);
return;
}
else
{
qr.push({i, a[i][1]});
clr(a[i][1]);
clr(i);
return;
}
}
for (int i = 0; i < n; i++)
{
if (mk[i]) continue;
if (a[i][1] == -1 && a[i][0] == -1) continue;
if (a[i][0] == -1 || !gd(i, a[i][0]))
{
if (a[i][1] == -1 !gd(i, a[i][1])) {cout << "NE" << endl; exit(0);}
vert.pb({i, a[i][1]});
clr(a[i][1]);
clr(i);
}
else
{
gorz.pb({i, a[i][0]});
clr(a[i][0]);
clr(i);
}
}
}
int main()
{
ios_base::sync_with_stdio(0); istream::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n;
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++)
for (int j = i + 1; j < n; j++)
if (x[i] == x[j]) {a[i][0] = j; a[j][0] = i;}
else if (y[i] == y[j]) {a[i][1] = j; a[j][1] = i;}
fnd();
while (sz(qr) > 0)
{
int fr = qr.front().F;
int sc = qr.front().S;
qr.pop();
if (gd(fr, sc))
{
if (x[fr] == x[sc]) gorz.pb({fr, sc}); else vert.pb({fr, sc});
}
fnd();
}
if (sz(vert) + sz(gorz) != n / 2) {cout << "NE" << endl; exit(0);}
cout << "DA" << endl;
for (auto it : gorz) cout << it.F + 1 << " " << it.S + 1 << endl;
for (auto it : vert) cout << it.F + 1 << " " << it.S + 1 << endl;
}
Compilation message
matching.cpp: In function 'void fnd()':
matching.cpp:134:31: error: expected ')' before '!' token
if (a[i][1] == -1 !gd(i, a[i][1])) {cout << "NE" << endl; exit(0);}
^
