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답안 #559248

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
559248 2022-05-09T14:38:39 Z Sweezy Cat in a tree (BOI17_catinatree) C++17
51 / 100
 1000 ms 42432 KB 
#include <bits/stdc++.h>
 
using namespace std;
#define int long long

#ifdef LOCAL
#include "algo/debug.h"
#else
#define debug(...) 42
#endif

#define all(a) (a).begin(), (a).end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define reps(i, s, n) for (int i = s; i < (n); ++i)
#define pb push_back
#define sz(a) (int) (a.size())

void solve() {
  int n, d;
  cin >> n >> d;
 
  if (d > n - 1) {
    cout << 1;
    return;
  }
 
  if (d == 0) {
    cout << n;
    return;
  }
 
  vector<vector<int>> g(n);
  reps(i, 1, n) {
    int p;
    cin >> p;
    g[p].push_back(i);
    g[i].push_back(p);
  }

  vector<int> s(n), used(n);
  function<void(int, int)> sizes = [&] (int v, int p) {
    s[v] = 1;
    for (auto &u : g[v]) {
      if (u != p && !used[u]) {
        sizes(u, v);
        s[v] += s[u];
      }
    }
  };

  function<int(int, int, int)> centroid = [&] (int v, int p, int n) {
    for (auto &u : g[v]) {
      if (u != p && !used[u] && s[u] > n / 2) {
        return centroid(u, v, n);
      } 
    }
    return v;
  };

  vector<vector<pair<int, int>>> centroids(n);
  function<void(int, int, int, int)> add_centroid = [&] (int v, int p, int centroid, int dist) {
    centroids[v].emplace_back(centroid, dist);
    for (auto &u : g[v]) {
      if (u != p && !used[u]) {
        add_centroid(u, v, centroid, dist + 1);
      }
    }
  };

  function<void(int)> decomposition1 = [&] (int v) {
    used[v] = 1;
    sizes(v, -1);

    add_centroid(v, -1, v, 0);

    for (auto &u : g[v]) {
      if (!used[u]) {
        decomposition1(centroid(u, v, s[u]));
      }
    }
  };
  decomposition1(0);

  int timer = 0;
  vector<pair<int, int>> vs;
  vector<int> tin(n), tout(n), par(n);
  function<void(int, int, int)> dfs = [&] (int v, int p, int dst) {
    par[v] = p;
    tin[v] = timer++;
    vs.emplace_back(dst, v);
    for (auto &u : g[v]) {
      if (u != p) {
        dfs(u, v, dst + 1);
      }
    }
    tout[v] = timer;
  };

  const int inf = 1e9;

  int res = 0;
  vector<int> mdist(n, inf);
  function<void(int)> decomposition2 = [&] (int v) {
    used[v] = 1;
    sizes(v, -1);

    vs.clear();
    dfs(v, -1, 0);
    sort(vs.begin(), vs.end());

    auto can = [&] (int ver, int dst) -> bool {
      for (auto &[centroid, dist_to_centroid] : centroids[ver]) {
        if (dist_to_centroid + mdist[centroid] < d) {
          return false;
        }
      }
      return true;
    };

    int m = sz(vs), r = m, cnt = 0;
    rep(l, m) {
      while (r - 1 >= l && vs[r - 1].first >= max(vs[l].first, d - vs[l].first)) {
        r--;
        int ver = vs[r].second;
        int dst = vs[r].first;
        if (can(ver, dst)) {
          cnt++;
          for (auto &[centroid, dist_to_centroid] : centroids[ver]) {
            mdist[centroid] = min(mdist[centroid], dist_to_centroid);
          }
        }
      }
      if (l == r) {
        res = max(res, cnt);
        break;
      } else {
        res = max(res, cnt + can(vs[l].second, vs[l].first));
      }
    }

    for (auto &[vd, ver] : vs) {
      for (auto &[centroid, dist_to_centroid] : centroids[ver]) {
        mdist[centroid] = inf;
      }
    }

    for (auto &u : g[v]) {
      if (!used[u]) {
        decomposition2(centroid(u, v, s[u]));
      }
    }
  };

  used.assign(n, 0);
  decomposition2(0);

  cout << res;
}
 
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  solve();
  return 0;
}

Subtask #1
11.0 / 11.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 212 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 0 ms 212 KB Output is correct
9 Correct 0 ms 212 KB Output is correct
10 Correct 0 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 1 ms 212 KB Output is correct
15 Correct 0 ms 212 KB Output is correct
16 Correct 0 ms 212 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 0 ms 212 KB Output is correct
19 Correct 0 ms 212 KB Output is correct
20 Correct 0 ms 212 KB Output is correct

Subtask #2
40.0 / 40.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 212 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 0 ms 212 KB Output is correct
9 Correct 0 ms 212 KB Output is correct
10 Correct 0 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 1 ms 212 KB Output is correct
15 Correct 0 ms 212 KB Output is correct
16 Correct 0 ms 212 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 0 ms 212 KB Output is correct
19 Correct 0 ms 212 KB Output is correct
20 Correct 0 ms 212 KB Output is correct
21 Correct 230 ms 1132 KB Output is correct
22 Correct 36 ms 340 KB Output is correct
23 Correct 32 ms 468 KB Output is correct
24 Correct 32 ms 464 KB Output is correct
25 Correct 162 ms 596 KB Output is correct
26 Correct 141 ms 716 KB Output is correct
27 Correct 131 ms 608 KB Output is correct
28 Correct 319 ms 788 KB Output is correct
29 Correct 324 ms 768 KB Output is correct
30 Correct 325 ms 788 KB Output is correct
31 Correct 313 ms 772 KB Output is correct
32 Correct 192 ms 844 KB Output is correct
33 Correct 177 ms 724 KB Output is correct
34 Correct 198 ms 724 KB Output is correct
35 Correct 185 ms 736 KB Output is correct
36 Correct 232 ms 764 KB Output is correct
37 Correct 227 ms 864 KB Output is correct
38 Correct 268 ms 964 KB Output is correct
39 Correct 263 ms 980 KB Output is correct
40 Correct 276 ms 1140 KB Output is correct

Subtask #3
0 / 49.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 212 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 0 ms 212 KB Output is correct
9 Correct 0 ms 212 KB Output is correct
10 Correct 0 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 1 ms 212 KB Output is correct
15 Correct 0 ms 212 KB Output is correct
16 Correct 0 ms 212 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 0 ms 212 KB Output is correct
19 Correct 0 ms 212 KB Output is correct
20 Correct 0 ms 212 KB Output is correct
21 Correct 230 ms 1132 KB Output is correct
22 Correct 36 ms 340 KB Output is correct
23 Correct 32 ms 468 KB Output is correct
24 Correct 32 ms 464 KB Output is correct
25 Correct 162 ms 596 KB Output is correct
26 Correct 141 ms 716 KB Output is correct
27 Correct 131 ms 608 KB Output is correct
28 Correct 319 ms 788 KB Output is correct
29 Correct 324 ms 768 KB Output is correct
30 Correct 325 ms 788 KB Output is correct
31 Correct 313 ms 772 KB Output is correct
32 Correct 192 ms 844 KB Output is correct
33 Correct 177 ms 724 KB Output is correct
34 Correct 198 ms 724 KB Output is correct
35 Correct 185 ms 736 KB Output is correct
36 Correct 232 ms 764 KB Output is correct
37 Correct 227 ms 864 KB Output is correct
38 Correct 268 ms 964 KB Output is correct
39 Correct 263 ms 980 KB Output is correct
40 Correct 276 ms 1140 KB Output is correct
41 Execution timed out 1086 ms 42432 KB Time limit exceeded
42 Halted 0 ms 0 KB -