#include <bits/stdc++.h> using namespace std; #define all(x) (x).begin(), (x).end() #define pii pair<int, int> #define ms(x) memset((x), -1, sizeof (x)) #define FOR(i, a, b) for (int i = (a); i <= (b); ++i) #define fi first #define se second #define MASK(i) (1 << (i)) #define BIT(x, i) (((x) >> (i)) & 1) const int MAX = (int) 1e6 + 5; const int MOD = (int) 1e9 + 7; int n; pii a[MAX]; namespace sub1{ bool check(){ return n <= 16; } int D[20], U[20], L[20], R[20], X[1000005], Y[1000005], ok[20], ok2 = 1; void process(const int &i, const int &j){ pii x = a[i], y = a[j]; if (x.fi == y.fi && x.se > y.se) U[j] = 1; if (x.fi == y.fi && x.se < y.se) D[j] = 1; if (x.fi < y.fi && x.se == y.se) L[j] = 1; if (x.fi > y.fi && x.se == y.se) R[j] = 1; ok[i] = 1; } void solve(){ for (int msk = 1; msk < MASK(n); msk++){ for (int i = 0; i < n; i++){ D[i] = U[i] = L[i] = R[i] = X[a[i].fi] = Y[a[i].se] = ok[i] = 0; ok2 = 1; } for (int i = 0; i < n; i++){ if (BIT(msk, i)){ X[a[i].fi]++; Y[a[i].se]++; if (X[a[i].fi] > 2) ok2 = 0; if (Y[a[i].se] > 2) ok2 = 0; for (int j = 0; j < n; j++){ if (i ^ j) process(i, j); } } } if (ok2){ bool ok3 = 1; for (int i = 0; i < n; i++){ if ((U[i] && D[i]) || (R[i] && L[i]) || ok[i]) ok[i] = 1; if (!ok[i]) ok3 = 0; } if (ok3){ for (int i = 0; i < n; i++){ if (BIT(msk, i)) cout << 1; else cout << 0; } return; } } } } } namespace sub3{ bool check(){ bool ok[1000005]; memset(ok, 0, sizeof ok); for (int i = 0; i < n; i++){ if (ok[a[i].fi]) return 0; ok[a[i].fi] = 1; } return 1; } void solve(){ vector<pii> X[10005]; bool answer[n + 5]; for (int i = 0; i < n; i++){ X[a[i].se].emplace_back(a[i].fi, i); } for (int i = 1; i < 10005; i++){ if (X[i].size()){ int mx = 0, mn = 0; for (int j = 0; j < (int)X[i].size(); j++){ if (X[i][mx].fi < X[i][j].fi) mx = j; if (X[i][mn].fi > X[i][j].fi) mn = j; } answer[X[i][mx].se] = answer[X[i][mn].se] = 1; } } for (int i = 0; i < n; i++) cout << answer[i]; } } signed main(){ #define name "slamp" if (fopen(name".inp", "r")){ freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); } ios::sync_with_stdio(false); cin.tie(nullptr); cin >> n; for (int i = 0; i < n; i++) cin >> a[i].fi >> a[i].se; if (sub1::check()) return sub1::solve(), 0; if (sub3::check()) return sub3::solve(), 0; return 0; }

Main.cpp: In function 'int main()':
Main.cpp:108:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |         freopen(name".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:109:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  109 |         freopen(name".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~