Submission #566088

#	Time	Username	Problem	Language	Result	Execution time	Memory
566088		shrimb	Building Skyscrapers (CEOI19_skyscrapers)	C++17	0 / 100	952 ms	117580 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);

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

struct cell {
    bool full, out;
    int x, y, ind;
    cell* adj[8], *parent = this, *prev = nullptr;
    vector<cell*> vec;
    cell(int a, int b, bool f) {
        full = f;
        x = a, y = b;
        cells[{x, y}] = this;
        if (f) ind = ID;
        if (f == 0) vec = {this};
        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] and !adj[d] -> full) Union(this, 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) {
    int u = c -> x, v = c -> y, ind = c -> ind;
    bool articulation = 0, isout = 0, sep;
    for (int i = 0 ; i < 8 ; i++) {
        if (c -> adj[i] and !c -> adj[i] -> full) isout |= Find(c -> adj[i]) -> out;
    }
    if (!isout) {
        expendable.erase(c);
        return;
    }
    for (int _d = 0 ; _d < 9 ; _d++) {
        int d = (_d == 8 ? 0 : _d);
        if (!c -> adj[d]) return;
        if (c -> adj[d] -> full) {
            sep = 1;
            continue;
        }
        if (d & 1) continue;
        auto cmp = Find(c -> adj[d]);
        if (cmp -> prev and sep == 1) {
            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;
        }
        cmp -> prev = c -> adj[d];
        sep = 0;
    }
    for (int d = 0 ; d < 8 ; d++) {
        if (!c -> adj[d] -> full) Find(c -> adj[d]) -> prev = nullptr;
    }
    if (isout and !articulation) expendable.insert(c);
    else expendable.erase(c);
}

void Union (cell *a, cell *b) {
    cell *x = Find(a), *y = Find(b);
    if (x -> vec > y -> vec) swap(x, y);
    for (auto &i : x -> vec) {
        for (int d = 0 ; d < 8 ; d++) if (i -> adj[d] and i -> adj[d] -> full) check(i -> adj[d]);
        y -> vec.push_back(i);
    }
    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);
    }
    for (int i = 0 ; i < n ; i++) {
        for (int d = 0 ; d < 8 ; d++) {
            if (!inp[i] -> adj[d]) inp[i] -> adj[d] = new cell(inp[i] -> x + dx[d], inp[i] -> y + dy[d], 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++) check(inp[i]);
    cout << "YES\n";
    vector<int> ans;
    while (expendable.size()) {
        auto cur = *expendable.begin();
        expendable.erase(expendable.begin());
        ans.push_back(cur -> ind + 1);
        *cur = cell(cur -> x, cur -> y, 0);
    }
    reverse(ans.begin(), ans.end());
    for (int i:  ans) cout << i << endl;
}

Compilation message (stderr)

skyscrapers.cpp:17:1: warning: multi-line comment [-Wcomment]
   17 | //\
      | ^
skyscrapers.cpp: In function 'void check(cell*)':
skyscrapers.cpp:77:9: warning: unused variable 'u' [-Wunused-variable]
   77 |     int u = c -> x, v = c -> y, ind = c -> ind;
      |         ^
skyscrapers.cpp:77:21: warning: unused variable 'v' [-Wunused-variable]
   77 |     int u = c -> x, v = c -> y, ind = c -> ind;
      |                     ^
skyscrapers.cpp:77:33: warning: unused variable 'ind' [-Wunused-variable]
   77 |     int u = c -> x, v = c -> y, ind = c -> ind;
      |                                 ^~~
skyscrapers.cpp:95:25: warning: 'sep' may be used uninitialized in this function [-Wmaybe-uninitialized]
   95 |         if (cmp -> prev and sep == 1) {
      |             ~~~~~~~~~~~~^~~~~~~~~~~~

• 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