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Submission #559271

# Submission time Handle Problem Language Result Execution time Memory
559271 2022-05-09T14:50:57 Z Sweezy Cat in a tree (BOI17_catinatree) C++17
51 / 100
 1000 ms 29132 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())

const int N = 2e5 + 5;
const int inf = 1e9;

vector<int> g[N];
int s[N], mdist[N], used[N], res, d;
vector<pair<int, int>> centroids[N], vs;

void 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];
    }
  }
}

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;
}

void 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);
    }
  }
}

void 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]));
    }
  }
}

void dfs(int v, int p, int dst) {
  vs.emplace_back(dst, v);
  for (auto &u : g[v]) {
    if (u != p) {
      dfs(u, v, dst + 1);
    }
  }
}

void 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]));
    }
  }
}

void solve() {
  fill(mdist, mdist + N, inf);

  int n;
  cin >> n >> d;
 
  if (d > n - 1) {
    cout << 1;
    return;
  }
 
  if (d == 0) {
    cout << n;
    return;
  }
 
  reps(i, 1, n) {
    int p;
    cin >> p;
    g[p].push_back(i);
    g[i].push_back(p);
  }
  
  sizes(0, -1);
  decomposition1(centroid(0, -1, n));

  fill(used, used + N, 0);
  sizes(0, -1);
  decomposition2(centroid(0, -1, n));

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

Subtask #1
11.0 / 11.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11220 KB Output is correct
2 Correct 6 ms 11220 KB Output is correct
3 Correct 7 ms 11220 KB Output is correct
4 Correct 5 ms 11220 KB Output is correct
5 Correct 6 ms 11220 KB Output is correct
6 Correct 6 ms 11220 KB Output is correct
7 Correct 5 ms 11220 KB Output is correct
8 Correct 6 ms 11220 KB Output is correct
9 Correct 6 ms 11220 KB Output is correct
10 Correct 6 ms 11184 KB Output is correct
11 Correct 5 ms 11220 KB Output is correct
12 Correct 6 ms 11220 KB Output is correct
13 Correct 6 ms 11220 KB Output is correct
14 Correct 6 ms 11220 KB Output is correct
15 Correct 6 ms 11280 KB Output is correct
16 Correct 6 ms 11280 KB Output is correct
17 Correct 7 ms 11272 KB Output is correct
18 Correct 6 ms 11280 KB Output is correct
19 Correct 6 ms 11220 KB Output is correct
20 Correct 6 ms 11220 KB Output is correct

Subtask #2
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11220 KB Output is correct
2 Correct 6 ms 11220 KB Output is correct
3 Correct 7 ms 11220 KB Output is correct
4 Correct 5 ms 11220 KB Output is correct
5 Correct 6 ms 11220 KB Output is correct
6 Correct 6 ms 11220 KB Output is correct
7 Correct 5 ms 11220 KB Output is correct
8 Correct 6 ms 11220 KB Output is correct
9 Correct 6 ms 11220 KB Output is correct
10 Correct 6 ms 11184 KB Output is correct
11 Correct 5 ms 11220 KB Output is correct
12 Correct 6 ms 11220 KB Output is correct
13 Correct 6 ms 11220 KB Output is correct
14 Correct 6 ms 11220 KB Output is correct
15 Correct 6 ms 11280 KB Output is correct
16 Correct 6 ms 11280 KB Output is correct
17 Correct 7 ms 11272 KB Output is correct
18 Correct 6 ms 11280 KB Output is correct
19 Correct 6 ms 11220 KB Output is correct
20 Correct 6 ms 11220 KB Output is correct
21 Correct 195 ms 11644 KB Output is correct
22 Correct 37 ms 11348 KB Output is correct
23 Correct 33 ms 11348 KB Output is correct
24 Correct 30 ms 11332 KB Output is correct
25 Correct 137 ms 11348 KB Output is correct
26 Correct 124 ms 11396 KB Output is correct
27 Correct 114 ms 11388 KB Output is correct
28 Correct 259 ms 11476 KB Output is correct
29 Correct 275 ms 11500 KB Output is correct
30 Correct 248 ms 11496 KB Output is correct
31 Correct 261 ms 11492 KB Output is correct
32 Correct 135 ms 11476 KB Output is correct
33 Correct 138 ms 11456 KB Output is correct
34 Correct 155 ms 11480 KB Output is correct
35 Correct 152 ms 11476 KB Output is correct
36 Correct 171 ms 11476 KB Output is correct
37 Correct 177 ms 11504 KB Output is correct
38 Correct 205 ms 11536 KB Output is correct
39 Correct 215 ms 11476 KB Output is correct
40 Correct 221 ms 11648 KB Output is correct

Subtask #3
0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11220 KB Output is correct
2 Correct 6 ms 11220 KB Output is correct
3 Correct 7 ms 11220 KB Output is correct
4 Correct 5 ms 11220 KB Output is correct
5 Correct 6 ms 11220 KB Output is correct
6 Correct 6 ms 11220 KB Output is correct
7 Correct 5 ms 11220 KB Output is correct
8 Correct 6 ms 11220 KB Output is correct
9 Correct 6 ms 11220 KB Output is correct
10 Correct 6 ms 11184 KB Output is correct
11 Correct 5 ms 11220 KB Output is correct
12 Correct 6 ms 11220 KB Output is correct
13 Correct 6 ms 11220 KB Output is correct
14 Correct 6 ms 11220 KB Output is correct
15 Correct 6 ms 11280 KB Output is correct
16 Correct 6 ms 11280 KB Output is correct
17 Correct 7 ms 11272 KB Output is correct
18 Correct 6 ms 11280 KB Output is correct
19 Correct 6 ms 11220 KB Output is correct
20 Correct 6 ms 11220 KB Output is correct
21 Correct 195 ms 11644 KB Output is correct
22 Correct 37 ms 11348 KB Output is correct
23 Correct 33 ms 11348 KB Output is correct
24 Correct 30 ms 11332 KB Output is correct
25 Correct 137 ms 11348 KB Output is correct
26 Correct 124 ms 11396 KB Output is correct
27 Correct 114 ms 11388 KB Output is correct
28 Correct 259 ms 11476 KB Output is correct
29 Correct 275 ms 11500 KB Output is correct
30 Correct 248 ms 11496 KB Output is correct
31 Correct 261 ms 11492 KB Output is correct
32 Correct 135 ms 11476 KB Output is correct
33 Correct 138 ms 11456 KB Output is correct
34 Correct 155 ms 11480 KB Output is correct
35 Correct 152 ms 11476 KB Output is correct
36 Correct 171 ms 11476 KB Output is correct
37 Correct 177 ms 11504 KB Output is correct
38 Correct 205 ms 11536 KB Output is correct
39 Correct 215 ms 11476 KB Output is correct
40 Correct 221 ms 11648 KB Output is correct
41 Execution timed out 1091 ms 29132 KB Time limit exceeded
42 Halted 0 ms 0 KB -