Submission #1053138

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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>
using namespace std;
typedef long long ll;
const int maxn = 100005;

set<pair<int,int>> st;
pair<int,int> a[maxn];
bool vis[maxn];
int n;

bool cmp(pair<int,int>a,pair<int,int>b){
    int tt =  min(a.first,a.second) - min(b.first, b.second);
    if(tt<0)return true;
    if(tt>0)return false;
    if(a.first==b.first)return a.second<b.second;
    if(a.second==b.second)return a.first<b.first;
    return true;
}

bool check_1() {
    if(a[1].first!=0||a[2].second!=0||a[1].second!=a[2].first)return false;
    return true;
}

bool check_2(int&ret) {
    if(n>2)sort(a+3,a+n+1, cmp);
    if(a[1].second==0)return false;
    vis[1] = vis[2] = 1;
    st.insert(a[1]);
    st.insert(a[2]);
    ret += a[1].second;
    if(a[1].second==1) return true;
    int cnt = 0;
    for(int i=3; i<=n; i++) {
        if(a[i].first + a[i].second != a[1].second) continue;
        if(st.find(a[i])!=st.end())continue;
        st.insert(a[i]);
        vis[i] = 1;
        cnt++;
    }
    return cnt == a[1].second - 1;
}

bool pd(int x,int y) {
    int x1 = x - 1, y1, x2, y2 = y - 1;
    for(int y1 = y-1; y1<=y+1; y1++)
        for(int x2=x-1; x2<=x+1; x2++) {
            if(st.find(make_pair(x1,y1))==st.end())continue;
            if(st.find(make_pair(x2,y2))==st.end())continue;
            return true;
        }
    return false;
}

bool check_3(int&ret) {
    for(int i=3; i<=n; i++) {
        if(vis[i])continue;
        pair<int,int> fa = make_pair(a[i].first-1,a[i].second-1);
        if(st.find(fa)!=st.end()) {
            vis[i]=1;
            ret++;
            st.insert(a[i]);
        } else {
            if(pd(a[i].first,a[i].second)) {
                vis[i] = 1;
                ret+=2;
                st.insert(a[i]);
            } else return false;
        }
    }
    return true;
}

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;
    }
    int ret = 0;
    if(!check_1()) {
        cout<<-1<<endl;
        return 0;
    }
    if(!check_2(ret)) {
        cout<<-1<<endl;
        return 0;
    }
    if(!check_3(ret)) {
        cout<<-1<<endl;
        return 0;
    }
    cout<<ret<<endl;
    return 0;
}

Submission Info

Judge Result