Submission #1053865

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Source Code Expand

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <cstring>
#include <ctime>
#include <set>
#include <map>
using namespace std;
typedef long long ll;
const int maxn = 100005;

int n;
pair<int,int> a[maxn];

bool check_1(){
  if(a[1].first!=0||a[2].second!=0||a[2].first!=a[1].second)return false;
  for(int i=3;i<=n;i++)
    if(a[i].first==0||a[i].second==0)return false;
  set<pair<int,int>>st;
  for(int i=1;i<=n;i++)st.insert(a[i]);
  for(int i=3;i<=n;i++){
    int cnt=0;
    for(int j=-1;j<=1;j++)
      if(st.find(make_pair(a[i].first-1,a[i].second+j))!=st.end()){
        cnt++;
        break;
      }
    for(int j=-1;j<=1;j++)
      if(st.find(make_pair(a[i].first+j,a[i].second-1))!=st.end()){
        cnt++;
        break;
      }
      if(cnt<2)return false;
  }
  return true;
}

bool cmp(pair<int,int> a,pair<int,int> b){
  int ta = a.first + a.second;
  int tb = b.first + b.second;
  return ta == tb ? a.first < b.first: ta < tb;
}

int cal(){
  int ret=0;
  sort(a+1,a+n+1,cmp);
  map<pair<int,int>,int>mp;
  for(int i=1;i<=n;i++){
    int pos = i;
    for(int j=i;j<=n;j++){
      if(a[j]!=a[i])break;
      pos=j;
    }
    if(mp.find(make_pair(a[i].first -1,a[i].second-1))!=mp.end()){
      ret+=mp[make_pair(a[i].first-1,a[i].second-1)];
      mp[a[i]] = 0;
    } else {
      int tmp =0;
      if(mp.find(make_pair(a[i].first-1,a[i].second+1))!=mp.end()){
        tmp = mp[make_pair(a[i].first-1,a[i].second+1)];
      }
      int cur = min(tmp, pos - i +1);
      ret+=cur;
      mp[a[i]] = pos-i+1;
    }
    i =pos;
  }
  return ret;
}

int main() {
   // freopen("in.cpp","r",stdin);
    cin>>n;
    for(int i=1; i<=n; i++) {
        int x,y;
        cin>>x>>y;
        a[i].first = x;
        a[i].second = y;
    }
    if(!check_1()){
      cout<<-1<<endl;
      return 0;
    }
    cout<<2*n-2-cal()<<endl;
    return 0;
}

Submission Info

Judge Result