Submission #597211

#	Time	Username	Problem	Language	Result	Execution time	Memory
597211		Valaki2	Building Skyscrapers (CEOI19_skyscrapers)	C++14	22 / 100	3594 ms	8112 KiB

skyscrapers

#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define mp make_pair
#define pii pair<int, int>
#define fi first
#define se second

const vector<pii > dir = {{-1, -1}, {-1, 0}, {-1, 1}, {0, -1}, {0, 1}, {1, -1}, {1, 0}, {1, 1}};
const vector<pii > dir_2 = {{-1, 0}, {0, -1}, {0, 1}, {1, 0}};

int n, type;
vector<pair<int, int> > v;
unordered_map<int, unordered_map<int, int> > which;
vector<int> ans;
set<int> doable;

bool has_neighbour(pii cur) {
    for(pii d : dir) {
        pii nei = mp(cur.fi + d.fi, cur.se + d.se);
        int nei_idx = which[nei.fi][nei.se];
        if(nei_idx != 0) {
            return true;
        }
    }
    return false;
}

int count_bfs(int start, int miss) {
    queue<int> q;
    vector<bool> vis(1 + n, false);
    q.push(start);
    vis[start] = true;
    while(!q.empty()) {
        int cur = q.front();
        q.pop();
        for(pii d : dir) {
            pii nei = mp(v[cur].fi + d.fi, v[cur].se + d.se);
            int nei_idx = which[nei.fi][nei.se];
            if(nei_idx != 0 && !vis[nei_idx] && nei_idx != miss) {
                q.push(nei_idx);
                vis[nei_idx] = true;
            }
        }
    }
    int res = 0;
    for(int i = 1; i <= n; i++) {
        if(vis[i]) {
            res++;
        }
    }
    return res;
}

queue<pii> q;
unordered_map<int, unordered_map<int, bool> > seen;

void upd_bfs() {
    while(!q.empty()) {
        pii cur = q.front();
        q.pop();
        for(pii d : dir_2) {
            pii nei = mp(cur.fi + d.fi, cur.se + d.se);
            int nei_idx = which[nei.fi][nei.se];
            if(nei_idx != 0) {
                doable.insert(nei_idx);
            } else {
                if(!seen[nei.fi][nei.se] && has_neighbour(nei)) {
                    q.push(nei);
                    seen[nei.fi][nei.se] = true;
                }
            }
        }
    }
}

void solve() {
    cin >> n >> type;
    v.assign(1 + n, mp(0, 0));
    int bottom_left = 1;
    for(int i = 1; i <= n; i++) {
        cin >> v[i].fi >> v[i].se;
        which[v[i].fi][v[i].se] = i;
        if(v[i].fi < v[bottom_left].fi) {
            bottom_left = i;
        }
    }
    if(count_bfs(1, -1) < n) {
        cout << "NO\n";
        return;
    }
    cout << "YES\n";
    set<int> rem;
    for(int i = 1; i <= n; i++) {
        rem.insert(i);
    }
    pii start = mp(v[bottom_left].fi - 1, v[bottom_left].se);
    q.push(start);
    seen[start.fi][start.se] = true;
    upd_bfs();
    while(!doable.empty()) {
        int to_rem = -1;
        for(int cur : doable) {
            int st = *rem.begin();
            if(st == cur) {
                st = *rem.rbegin();
            }
            if(count_bfs(st, cur) >= (int) rem.size() - 1) {
                // cur can be removed
                to_rem = cur;
                break;
            }
        }
        ans.pb(to_rem);
        rem.erase(to_rem);
        doable.erase(to_rem);
        q.push(v[to_rem]);
        which[v[to_rem].fi][v[to_rem].se] = 0;
        upd_bfs();
    }
    reverse(ans.begin(), ans.end());
    for(int cur : ans) {
        cout << cur << "\n";
    }
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
    return 0;
}

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