Submission #2484043

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Source Code Expand

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cmath>
#include <iomanip>
#include <cassert>
#include <bitset>
using namespace std;

typedef pair<int, int> P;
#define rep(i, n) for (int i=0; i<(n); i++)
#define all(c) (c).begin(), (c).end()
#define uniq(c) c.erase(unique(all(c)), (c).end())
#define index(xs, x) (int)(lower_bound(all(xs), x) - xs.begin())
#define _1 first
#define _2 second
#define pb push_back
#define INF 1145141919
#define MOD 1000000007

int N;
int A[100000], B[100000];
map<P, bool> exist;
map<P, int> CA, CB;

signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  cin >> N;
  rep(i, N) cin >> A[i] >> B[i];
  int zero_a = 0, zero_b = 0;
  rep(i, N) zero_a += A[i]==0, zero_b += B[i]==0;
  if (A[0] != 0 || B[1] != 0 || zero_a != 1 || zero_b != 1) {
    cout << -1 << "\n";
    return 0;
  }
  rep(i, N) exist[P(A[i], B[i])] = true;
  rep(i, N) {
    int a = A[i], b = B[i];
    if (a > 0 && !exist[P(a-1, b-1)] && !exist[P(a-1, b)] && !exist[P(a-1, b+1)]) {
      cout << -1 << "\n";
      return 0;
    }
    if (b > 0 && !exist[P(a-1, b-1)] && !exist[P(a, b-1)] && !exist[P(a+1, b-1)]) {
      cout << -1 << "\n";
      return 0;
    }
  }
  int sum = 0;
  rep(i, N) {
    int a = A[i], b = B[i];
    if (exist[P(a-1, b-1)]) sum++;
    else {
      //cout<<"("<<a<<","<<b<<")\n";
      if (a > 0) CA[P(a, b)]++;
      if (b > 0) CB[P(a, b)]++;
    }
  }
  for (auto &p : CA) {
    int a = p._1._1, b = p._1._2;
    int num = min(p._2, CB[P(a-1, b+1)]);
    p._2 -= num;
    CB[P(a-1, b+1)] -= num;
    //cout<<"("<<a<<","<<b<<")<->("<<a-1<<","<<b+1<<") * "<<num<<"\n";
    sum += num;
  }
  for (auto p : CA) sum += p._2;
  for (auto p : CB) sum += p._2;
  sum--;
  cout << sum << "\n";
  return 0;
}

Submission Info

Judge Result