Submission #1096006

#	Time	Username	Problem	Language	Result	Execution time	Memory
1096006		yoav_s	Building Skyscrapers (CEOI19_skyscrapers)	C++17	22 / 100	3550 ms	265300 KiB

skyscrapers

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<ll> v;
typedef vector<v> vv;
typedef vector<vv> vvv;
typedef pair<ll, ll> p;
typedef vector<p> vp;
typedef vector<vp> vvp;
typedef vector<vvp> vvvp;
typedef pair<ll, p> tri;
typedef vector<tri> vtri;
typedef vector<vtri> vvtri;
typedef vector<vvtri> vvvtri;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<vvb> vvvb;

#define f first
#define s second
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(),(v).end()

const ll INF = 1e18;
const ll mod = 1e9 + 7;

p getParent(p cur, vvp &dsuParent)
{
    if (dsuParent[cur.f][cur.s] == cur) return cur;
    return dsuParent[cur.f][cur.s] = getParent(dsuParent[cur.f][cur.s], dsuParent);
}

vp getNeighbors(p pos, ll maxX, ll maxY)
{
    vp neighbors; ll i = pos.f; ll j = pos.s;
    if (i - 1 >= 0)
    {
        neighbors.eb(i - 1, j);
    }
    if (i + 1 < maxX)
    {
        neighbors.eb(i + 1, j);
    }
    if (j - 1 >= 0)
    {
        neighbors.eb(i, j - 1);
    }
    if (j + 1 < maxY)
    {
        neighbors.eb(i, j + 1);
    }
    return neighbors;    
}

int main()
{
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    ll n, t;
    cin >> n >> t;
    vp cells(n);
    for (ll i=  0; i < n; i++) cin >> cells[i].f >> cells[i].s;
    v relevantX, relevantY;
    for (ll i = 0; i < n; i++)
    {
        relevantX.pb(cells[i].f - 1);
        relevantX.pb(cells[i].f);
        relevantX.pb(cells[i].f + 1);
        relevantY.pb(cells[i].s - 1);
        relevantY.pb(cells[i].s);
        relevantY.pb(cells[i].s + 1);
    }
    sort(all(relevantX)); sort(all(relevantY));
    relevantX.erase(unique(all(relevantX)), relevantX.end()); relevantY.erase(unique(all(relevantY)), relevantY.end());
    map<ll, ll> xShrink;
    map<ll, ll> yShrink;
    for (ll i = 0; i < relevantX.size(); i++) xShrink[relevantX[i]] = i + 1;
    for (ll i = 0; i < relevantY.size(); i++) yShrink[relevantY[i]] = i + 1;
    for (ll i = 0; i < n; i++) cells[i] = p(xShrink[cells[i].f], yShrink[cells[i].s]);
    ll maxX = relevantX.size() + 2, maxY = relevantY.size() + 2;
    vv occupied(maxX, v(maxY, -1));
    for (ll i = 0; i < n; i++) occupied[cells[i].f][cells[i].s] = i;
    set<ll> remaining;
    v available;
    set<ll> avSet;
    for (ll i = 0; i < n; i++) remaining.insert(i);
    v order;
    vb possible(n, false);
    vv adjacentStructures(n);
    for (ll i = 0; i < n; i++)
    {
        for (ll j = i + 1; j < n; j++)
        {
            if (abs(cells[i].f - cells[j].f) <= 1 && abs(cells[i].s - cells[j].s) <= 1)
            {
                adjacentStructures[i].pb(j);
                adjacentStructures[j].pb(i);
            }
        }
    }
    vb visited(n, false);
    stack<ll> dfs; dfs.push(0);
    ll cnt = 0;
    while (!dfs.empty())
    {
        auto top = dfs.top();
        dfs.pop();
        if (visited[top]) continue;
        visited[top] = true; cnt++;
        for (ll x : adjacentStructures[top]) dfs.push(x);
    }
    if (cnt != n)
    {
        cout << "NO\n";
        return 0;
    }
    vvp dsuParent(maxX, vp(maxY));
    for (ll i = 0; i < maxX; i++) for (ll j = 0; j < maxY; j++) dsuParent[i][j] = p(i, j);
    vv dsuSize(maxX, v(maxY, 1));
    for (ll i = 0; i < maxX; i++)
    {
        for (ll j = 0; j < maxY; j++)
        {
            if (occupied[i][j] != -1) continue;
            vp neighbors = getNeighbors(p(i, j), maxX, maxY);
            for (auto x : neighbors)
            {
                if (occupied[x.f][x.s] != -1) continue;
                p p1 = getParent(p(i, j), dsuParent), p2 = getParent(x, dsuParent);
                if (p1 == p2) continue;
                if (dsuSize[p1.f][p1.s] > dsuSize[p2.f][p2.s]) swap(p1,p2);
                dsuParent[p1.f][p1.s] = p2;
                dsuSize[p2.f][p2.s] += dsuSize[p1.f][p1.s];
            }
        }
    }
    for (ll i = 0; i < n; i++)
    {
        vp neighbors = getNeighbors(cells[i], maxX, maxY);
        bool hasNeighbor = false;
        p expected = getParent(p(0, 0), dsuParent);
        for (auto y : neighbors)
        {
            if (getParent(y, dsuParent) == expected) hasNeighbor = true;
        }
        if (hasNeighbor && avSet.count(i) == 0)
        {
            available.pb(i);
            avSet.insert(i);
        }
    }
    for (ll i = n - 1; i >= 0; i--)
    {
        bool done = false;
        for (ll j = 0; j < available.size(); j++)
        {
            ll x = available[j];
            vp neighbors = getNeighbors(cells[x], maxX, maxY);
            if (i > 1)
            {
                vb visited(n, false);
                auto ptr = remaining.begin();
                if (*ptr == x) ptr++;
                ll start = *ptr;
                stack<ll> dfs; dfs.push(start);
                ll cnt = 0;
                while (!dfs.empty())
                {
                    auto top = dfs.top();
                    dfs.pop();
                    if (remaining.count(top) == 0 || top == x || visited[top]) continue;
                    visited[top] = true; cnt++;
                    for (ll x : adjacentStructures[top]) dfs.push(x);
                }
                if (cnt != remaining.size() - 1)
                {
                    continue;
                }
            }
            occupied[cells[x].f][cells[x].s] = -1;
            for (auto y : neighbors)
            {
                if (occupied[y.f][y.s] == -1)
                {
                    p p1 = getParent(y, dsuParent), p2 = getParent(cells[x], dsuParent);
                    if (p1 == p2) continue;
                    if (dsuSize[p1.f][p1.s] > dsuSize[p2.f][p2.s]) swap(p1,p2);
                    dsuParent[p1.f][p1.s] = p2;
                    dsuSize[p2.f][p2.s] += dsuSize[p1.f][p1.s];
                }
            }
            p expect = getParent(p(0, 0), dsuParent);
            p par = getParent(cells[x], dsuParent);
            if (par == expect)
            {
                for (auto y : neighbors)
                {
                    if (occupied[y.f][y.s] == -1)
                    {
                        vp nei = getNeighbors(y, maxX, maxY);
                        for (auto z : nei)
                        {
                            if (occupied[z.f][z.s] != -1 && avSet.count(occupied[z.f][z.s]) == 0)
                            {
                                available.pb(occupied[z.f][z.s]);
                                avSet.insert(occupied[z.f][z.s]);
                            }
                        }
                    }
                    else if (avSet.count(occupied[y.f][y.s]) == 0)
                    {
                        available.pb(occupied[y.f][y.s]);
                        avSet.insert(occupied[y.f][y.s]);
                    }
                }
            }
            remaining.erase(x);
            available.erase(available.begin() + j);
            order.pb(x);
            done = true;
            break;
        }
        assert(done);
    }
    reverse(all(order));
    cout << "YES\n";
    for (ll x : order) cout << x + 1 << "\n";
    return 0;
}

Compilation message (stderr)

skyscrapers.cpp: In function 'int main()':
skyscrapers.cpp:79:22: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |     for (ll i = 0; i < relevantX.size(); i++) xShrink[relevantX[i]] = i + 1;
      |                    ~~^~~~~~~~~~~~~~~~~~
skyscrapers.cpp:80:22: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   80 |     for (ll i = 0; i < relevantY.size(); i++) yShrink[relevantY[i]] = i + 1;
      |                    ~~^~~~~~~~~~~~~~~~~~
skyscrapers.cpp:157:26: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  157 |         for (ll j = 0; j < available.size(); j++)
      |                        ~~^~~~~~~~~~~~~~~~~~
skyscrapers.cpp:177:25: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::set<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  177 |                 if (cnt != remaining.size() - 1)
      |                     ~~~~^~~~~~~~~~~~~~~~~~~~~~~

• 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