Submission #566157

#	Time	Username	Problem	Language	Result	Execution time	Memory
566157		shrimb	Building Skyscrapers (CEOI19_skyscrapers)	C++17	100 / 100	2576 ms	320740 KiB

skyscrapers

// #pragma GCC optimize ("Ofast")
// #pragma GCC target ("avx,avx2,fma")

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

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<class x>
using ordered_set = tree<x, null_type,less<x>, rb_tree_tag,tree_order_statistics_node_update>;

#define int long long
#define endl '\n'
#define mod 1000000007
//\
#define mod 1686876991

const int maxn = 150001;
const int dx[] = {1, 1, 0, -1, -1, -1,  0,  1};
const int dy[] = {0, 1, 1,  1,  0, -1, -1, -1};
const int inv[] = {4, 5, 6, 7, 0, 1, 2, 3};
struct cell;

int n, t, ID;
cell* Find (cell *x);
void check (cell *c);
void Union (cell *a, cell *b);
bitset<maxn> deleted;

map<pair<int,int>, cell*> cells;

struct cell {
    bool full = 0, out = 0;
    int x, y, ind;
    cell* adj[8], *parent = this, *prev = nullptr;
    vector<cell*> vec;
    cell(int a, int b, bool f) {
        // cerr << endl << a <<  " " << b << endl;
        full = f;
        x = a, y = b;
        cells[{x, y}] = this;
        if (f == 0) vec = {this};
        else ind = ID;
        for (int d = 0 ; d < 8 ; d++) {
            int u = x + dx[d];
            int v = y + dy[d];
            auto it = cells.find({u, v});
            if (it != cells.end()) {
                adj[d] = it -> second;
                it -> second -> adj[inv[d]] = this;
            }
            else  adj[d] = nullptr;
        }
        if (f == 0) {
            for (int d = 0 ; d < 8 ; d += 2) {
                if (adj[d]) {
                    if (!adj[d] -> full) Union(this, adj[d]);
                }
            }
            for (int d = 0 ; d < 8 ; d++) {
                if (adj[d] and adj[d] -> full) check(adj[d]);
            }
        }
    }
};
cell* inp[maxn];

struct cmp {
    bool operator () (cell *a, cell *b) const {
        return a -> ind > b -> ind;
    }
};

set<cell*,cmp> expendable;


cell* Find (cell *x) {
    return x == x -> parent ? x : x -> parent = Find(x -> parent);
}

void check (cell *c) {
    bool articulation = 0, isout = 0, sep = 0;
    // cerr << c -> ind << " " << articulation <<  endl;
    for (int i = 0 ; i < 8 ; i++) if (!c -> adj[i]) return;
    for (int i = 0 ; i < 8 ; i+=2) {
        if (!c -> adj[i] -> full) isout |= Find(c -> adj[i]) -> out;
    }
    if (!isout) {
        expendable.erase(c);
        return;
    }
    // cerr << c -> x << " " << c -> y << endl;
    for (int _d = 0 ; _d < 9 ; _d++) {
        int d = (_d == 8 ? 0 : _d);
        if (c -> adj[d] -> full) {
            sep = 1;
            continue;
        }
        if (d & 1) continue;
        auto cmp = Find(c -> adj[d]);
        // cerr << "kfdjasdd: " << d << " " << cmp -> out << " | ";
        if (cmp -> prev and sep == 1) {
            // cerr << cmp -> prev -> x << " " << cmp -> prev -> y << endl;
            bool bad = 0;
            for (int __d = _d ; !bad ; __d++) {
                int d2 = __d % 8;
                if (c -> adj[d2] == cmp -> prev) break;
                if (c -> adj[d2] -> full) bad = 1;
            }
            if (bad) {
                articulation = 1;
                break;
            }
        }
        // cerr << endl;
        cmp -> prev = c -> adj[d];
        sep = 0;
    }
    // cerr << articulation << endl;
    for (int d = 0 ; d < 8 ; d++) {
        if (!c -> adj[d] -> full) {
            Find(c -> adj[d]) -> prev = nullptr;
            // cerr << Find(c -> adj[d]) -> prev << endl;
        }
    }
    // cerr << c -> x << " " << c -> y << " " << isout << " ..." << articulation << endl;
    if (!articulation) expendable.insert(c);
    else expendable.erase(c);
}

void Union (cell *a, cell *b) {
    cell *x = Find(a), *y = Find(b);
    if (x == y) return;
    if (x -> vec.size() > y -> vec.size()) swap(x, y);
    x -> parent = y;
    y -> out |= x -> out;
    for (auto &i : x -> vec) {
        y -> vec.push_back(i);
        for (int d = 0 ; d < 8 ; d++) if (i -> adj[d] and i -> adj[d] -> full) check(i -> adj[d]);
    }
    x -> vec.clear();
}

signed main () {
    cin.tie(0)->sync_with_stdio(0);
    cin >> n >> t;
    for (int i = 0 ; i < n ; i++) {
        ID = i;
        int x, y;
        cin >> x >> y;
        inp[i] = new cell(x, y, 1);
    }
    int idx = 0;
    for (int i = 0 ; i < n ; i++) {
        if (inp[i] -> x < inp[idx] -> x) idx = i;
        else if (inp[i] -> x == inp[idx] -> x and inp[i] -> y < inp[idx] -> y) idx = i;
    }
    inp[idx] -> adj[4] = new cell(inp[idx] -> x + dx[4], inp[idx] -> y + dy[4], 0);
    inp[idx] -> adj[4] -> out = 1;
    // cerr << idx << endl;
    for (int i = 0 ; i < n ; i++) {
        // cerr << i << ": ";
        for (int d = 0 ; d < 8 ; d++) {
            // cerr << d << " ";
            if (!inp[i] -> adj[d]) {
                new cell(inp[i] -> x + dx[d], inp[i] -> y + dy[d], 0);
            }
        }
    }
    // assert(0);
    if (n > 1) {
        for (int i = 0 ; i < n ; i++) {
            bool good = 0;
            for (int d = 0 ; d < 8 ; d++) {
                if (inp[i] -> adj[d] -> full) good = 1;
            }
            if (!good) {
                cout << "NO\n";
                return 0;
            }
        }
    }

    // for (int i = 0 ; i < n ; i++) {
    //     for (auto j : inp[i] -> adj) {
    //         if (!j -> full)
    //         for (auto k : j -> adj) {
    //             if (k and !k -> full) Union(j, k);
    //         }
    //     }
    // }

    for (int i = 0 ; i < n ; i++) check(inp[i]);
    cout << "YES\n";
    vector<int> ans;
    // cerr << "alkjdaskldjaslkjlkadjlkasjdlkasj\n";
    while (expendable.size()) { 
        auto cur = *expendable.begin();
        expendable.erase(expendable.begin());
        ans.push_back(cur -> ind + 1);
        deleted[cur -> ind] = 1;
        new cell(cur -> x, cur -> y, 0);
    }
    reverse(ans.begin(), ans.end());
    for (int i:  ans) cout << i << endl;
}

/*
9
2
0 0 0 1
1 -1 2 -1
3 0 3 1
1 2 2 2
1 0
*/

Compilation message (stderr)

skyscrapers.cpp:17:1: warning: multi-line comment [-Wcomment]
   17 | //\
      | ^

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