#include <bits/stdc++.h> #define tl 5007 #define nl 1000007 #define fi first #define se second #define sz() size() #define ll long long #define ps push_back #define vi vector<int> #define pii pair<int,int> #define vpi vector<pair<int,int>> using namespace std; mt19937_64 rd(time(0)); long long Random( long long l , long long r ) { return l + rd() % (r-l+1) ; } int n; struct lamp{ int x, y, id; } a[nl]; void Input() { cin >> n; for( int i = 1 ; i <= n ; i ++ ) cin >> a[i].x >> a[i].y, a[i].id = i; } namespace Sub2 { bool p[22]; bool ck() { for( int i = 1 ; i <= n ; i ++ ) { if(p[i] == 1) continue; int xa = 0, xb = 0; int ya = 0, yb = 0; for( int j = 1 ; j <= n ; j ++ ) if(p[j]) { if(a[j].y == a[i].y) { xa += (a[j].x < a[i].x); xb += (a[j].x > a[i].x); } if(a[j].x == a[i].x) { ya += (a[j].y < a[i].y); yb += (a[j].y > a[i].y); } } if( min(xa,xb) == 0 && min(ya,yb) == 0 ) return false; } for( int i = 1 ; i <= n ; i ++ ) if(p[i]) { int cntx = 0; int cnty = 0; for( int j = 1 ; j <= n ; j ++ ) if(j != i && p[j]) { cntx += a[i].x == a[j].x; cnty += a[i].y == a[j].y; } if(max(cntx,cnty) >= 2) return false; } return true; } void Solve() { for( int mask = 1; mask < (1<<n) ; mask ++ ) { for( int i = 0 ; i < n ; i ++ ) p[i+1] = (mask>>i)&1; if(ck()) { for( int i = 1 ; i <= n ; i ++ ) cout << p[i]; break; } } } } namespace Sub3 { bool OK() { vi cnt(nl,0); for( int i = 1 ; i <= n ; i ++ ) cnt[a[i].x] ++; for( int i = 1 ; i <= nl-7 ; i ++ ) if(cnt[i] > 2) return false; return true; } void Solve() { sort(a+1,a+1+n, [&]( lamp u, lamp v){ if(u.y == v.y) return u.x < v.x; return u.y < v.y; }); vi p(n+3,0); p[a[1].id] = 1; for( int i = 2 ; i <= n+1 ; i ++ ) if(a[i].y > a[i-1].y || i > n) { p[a[i-1].id] = p[a[i].id] = 1; } for( int i = 1 ; i <= n ; i ++ ) cout << p[i]; } } unordered_map<int,bool> vs[nl]; void Test() { ofstream out("SLAMP.inp"); int N = 10; out << N << '\n'; vector<bool> cnt(nl,0); int mx = nl-7; for( int i = 1 ; i <= N ; i += 2 ) { int x = Random(1,mx); while(cnt[x] == 1) x = Random(1,mx); int v = Random(1,mx); while(vs[x][v] == 1) v = Random(1,mx); out << x << ' ' << v << '\n'; vs[x][v] = true; while(vs[x][v] == 1) v = Random(1,mx); out << x << ' ' << v << '\n'; vs[x][v] = true; cnt[x] = 1; } } int main() { #define Beta "SLAMP" if( fopen( Beta ".INP", "r" ) ){ freopen( Beta ".INP", "r", stdin ) ; freopen( Beta ".OUT", "w", stdout ) ; } ios_base::sync_with_stdio(false); cin.tie(nullptr); //Test(); Input(); if(n <= 20) Sub2::Solve(); else Sub3::Solve(); }

Main.cpp: In function 'int main()':
Main.cpp:166:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  166 |         freopen( Beta ".INP", "r", stdin )  ;
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:167:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  167 |         freopen( Beta ".OUT", "w", stdout ) ;
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~