Submission #1053921

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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||a[1].second==0)return false;
  for(int i=3;i<=n;i++)
    if(a[i].first==0||a[i].second==0||a[i].first+a[i].second<a[1].first+a[1].second)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,f;
  //map<pair<int,int>,int>f[2];
  for(int i=1;i<=n;i++){
    int pos = i;
    vector<pair<int,int>>v;
    v.push_back(a[i]);
    for(int j = i;j<=n;j++){
      if(a[j].first + a[j].second!=a[i].first + a[i].second)break;
      pos = j;
      if(mp.find(a[j])==mp.end())mp[a[j]]=1;
      else mp[a[j]]+=1;
      f[a[j]]=mp[a[j]];
      //f[0][a[j]] = f[1][a[j]] = -1;
      if(j>i&&a[j]!=a[i])v.push_back(a[j]);
    }/*
    f[0][v[0]]=0;
    if(mp.find(make_pair(v[0].first-1,v[0].second-1))!=mp.end()){
      f[1][v[0]] = mp[v[0]];
    }
    for(int j=0;j+1<v.size();j++){
      if(f[0][v[j]]!=-1){
        if(v[j].first == v[j+1].first - 1){
          f[0][v[j+1]] = max(f[0][v[j+1]],f[0][v[j]] + min(mp[v[j]],mp[v[j+1]]));
        } else {
          f[0][v[j+1]] = max(f[0][v[j+1]],f[0][v[j]]);
        }
        if(mp.find(make_pair(v[j+1].first-1,v[j+1].second-1))!=mp.end()){
          f[1][v[j+1]] = max(f[1][v[j+1]],f[0][v[j]]+mp[v[j+1]]);
        }
      }
      if(f[1][v[j]]!=-1){
        f[0][v[j+1]] = max(f[0][v[j+1]],f[1][v[j]]);
        if(mp.find(make_pair(v[j+1].first-1,v[j+1].second-1))!=mp.end()){
          f[1][v[j+1]] = max(f[1][v[j+1]],f[1][v[j]]+mp[v[j+1]]);
        }
      }
    }
    ret += max(0, max(f[0][v[v.size()-1]],f[1][v[v.size()-1]]));
    */
    for(int j=1;j<v.size();j++){
      if(v[j-1].first+1==v[j].first){
        int tt =min(mp[v[j-1]],mp[v[j]]);
        ret+=tt;
        f[v[j-1]] = min(f[v[j-1]],mp[v[j-1]]-tt);
        f[v[j]] = min(f[v[j]],mp[v[j]]-tt);
      }
    }
    for(int i=0;i<v.size();i++){
      if(mp.find(make_pair(v[i].first-1,v[i].second-1))!=mp.end()){
        ret+=f[v[i]];
      }
    }
    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