Submission #347115

#	Time	Username	Problem	Language	Result	Execution time	Memory
347115		doowey	Building Skyscrapers (CEOI19_skyscrapers)	C++14	0 / 100	1417 ms	138900 KiB

skyscrapers

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

#define fi first
#define se second
#define mp make_pair
#define fastIO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

int dir[8][2] = {{-1,-1},{0,-1},{+1,-1},{+1,0},{+1,+1},{0,+1},{-1,+1},{-1,0}};
int dv[4][2] = {{-1,0},{+1,0},{0,+1},{0,-1}};

const int N = 151169;
const int M = (int)2e6;
pii vv[M];
set<int> Q[M];
int par[M];
map<pii,int> indx;
map<pii,int> emp;
map<pii,int> vis;
int deg[N];
int xi[N], yi[N];

int cnt = 0;

void dfs(pii cur){
    cnt ++ ;
    vis[cur]=true;
    pii go;
    for(int p = 0 ; p < 8 ; p ++ ){
        go = mp(cur.fi+dir[p][0],cur.se+dir[p][1]);
        if(indx.count(go) && !vis[go]){
            dfs(go);
        }
    }
}

pii low = mp((int)1e9 + 7, (int)1e9 + 7);

int fin(int x){
    if(par[x]==x) return x;
    return par[x]=fin(par[x]);
}

void unite(int u, int v){
    u=fin(u);
    v=fin(v);
    if(u==v) return;
    if(Q[u].size() > Q[v].size()) swap(u,v);
    for(auto x : Q[u]){
        Q[v].insert(x);
    }
    Q[u].clear();
    par[u]=v;
}


bool can_remove(pii yi){
    vector<int> c;
    pii nx;
    for(int d = 0; d < 8 ; d ++ ){
        nx = mp(yi.fi + dir[d][0], yi.se + dir[d][1]);
        if(indx[nx] > 0) {
            c.push_back(-1);
        }
        else {
            c.push_back(fin(emp[nx]));
        }
    }
    int cnt = 0;
    for(auto x : c) if(x == -1) cnt ++ ; // full cells
    if(cnt <= 1) return true;
    int p, q;
    for(int i = 0 ; i < 8; i += 2 ){
        q = (i + 1) % 8;
        p = (i - 1 + 8) % 8;
        if(c[i] == -1 && c[p] >= 0 && c[p] == c[q]){ // cut off
            return false;
        }
    }
    if(c[1] >= 0 && c[1] == c[5] && min({c[0],c[7],c[6]}) == -1 && min({c[2],c[3],c[4]}) == -1){
        return false;
    }
    if(c[7] >= 0 && c[7] == c[3] && min({c[0],c[1],c[2]}) == -1 && min({c[4],c[5],c[6]}) == -1){
        return false;
    }
    return true;
}

int main(){
    fastIO;
    int n, typ;
    cin >> n >> typ;
    for(int i = 1; i <= n; i ++ ){
        cin >> xi[i] >> yi[i];
        indx[mp(xi[i],yi[i])]=i;
    }
    pii nx;
    int id=0;
    for(int i = 1;i <= n; i ++ ){
        for(int d = 0; d < 8 ; d ++ ){
            nx = mp(xi[i]+dir[d][0],yi[i]+dir[d][1]);
            if(indx.count(nx)){
                continue;
            }
            if(!emp.count(nx)){
                emp[nx]=id;
                vv[id]=nx;
                par[id]=id;
                id++;
            }
        }
    }
    for(int i = 0 ; i < id; i ++ ){
        for(int q = 0; q < 4; q ++ ){
            nx = mp(vv[i].fi+dv[q][0],vv[i].se+dv[q][1]);
            if(indx.count(nx)){
                Q[i].insert(indx[nx]);
            }
        }
    }
    for(int i = 0 ; i < id; i ++ ){
        low = min(low, vv[i]);
        for(int j = 0 ; j < 4; j ++ ){
            nx = mp(vv[i].fi+dv[j][0], vv[i].se+dv[j][1]);
            if(emp.count(nx)){
                unite(i,emp[nx]);
            }
        }
    }
    dfs(mp(xi[1],yi[1]));
    if(cnt != n){
        cout << "NO\n";
        return 0;
    }
    vector<int> ord;
    int cid;
    cout << "YES\n";
    set<int> bad;
    int idx;
    for(int i = 0 ; i < n; i ++ ){
        cid = fin(emp[low]);
        while(!Q[cid].empty()){
            auto it = Q[cid].end();
            -- it;
            if(can_remove(mp(xi[*it],yi[*it]))){
                idx = *it;
                ord.push_back(idx);
                Q[cid].erase(it);
                indx[mp(xi[idx],yi[idx])]=0;
                par[id]=id;
                vv[id]=mp(xi[idx],yi[idx]);
                emp[mp(xi[idx],yi[idx])]=id;
                for(int d = 0 ; d < 8 ; d ++ ){
                    nx = mp(xi[idx]+dir[d][0], yi[idx]+dir[d][1]);
                    if(indx[nx]>0){
                        Q[fin(emp[nx])].erase(idx);
                    }
                }
                for(int d = 0; d < 4; d ++ ){
                    nx = mp(xi[idx]+dir[d][0], yi[idx]+dir[d][1]);
                    if(indx[nx]>0){
                        Q[id].insert(indx[nx]);
                    }
                }
                for(int d = 0; d < 4 ; d ++ ){
                    nx = mp(xi[idx]+dv[d][0],yi[idx]+dv[d][1]);
                    if(emp.count(nx)){
                        unite(id,emp[nx]);
                    }
                }
                id ++ ;
                break;
            }
            else{
                bad.insert(*it);
                Q[cid].erase(it);
            }
        }
        cid = fin(emp[low]);
    }
    reverse(ord.begin(),ord.end());
    for(auto yy : ord){
        cout << yy << "\n";
    }
    return 0;
}

• Subtask 1: 0 / 8
• Subtask 2: 0 / 14
• Subtask 3: 0 / 12
• Subtask 4: 0 / 17
• Subtask 5: 0 / 20
• Subtask 6: 0 / 10
• Subtask 7: 0 / 19