Submission #722095

#	Time	Username	Problem	Language	Result	Execution time	Memory
722095		viwlesxq	Easter Eggs (info1cup17_eastereggs)	C++17	0 / 100	14 ms	464 KiB

eastereggs

#include <bits/stdc++.h>
#include "grader.h"

using namespace std;

typedef int64_t ll;
typedef string str;

int findEgg(int n, vector <pair <int, int>> edges) {
  vector <int> g[n + 1];
  int par[n + 1], sz[n + 1];
  vector <bool> used(n + 1, false);
  for (auto [a, b] : edges) {
    g[a].push_back(b);
    g[b].push_back(a);
  }
  function <void(int, int)> prepare = [&](int v, int p) {
    par[v] = p;
    sz[v] = 1;
    for (int to : g[v]) {
      if (to == p) {
        continue;
      }
      prepare(to, v);
      sz[v] += sz[to];
    }
  };
  prepare(1, -1);
  function <int(int, int)> get_centroid = [&](int v, int p) {
    for (int to : g[v]) {
      if (to == p || used[to]) {
        continue;
      }
      if (sz[to] * 2 >= n) {
        return get_centroid(to, v);
      }
    }
    return v;
  };
  vector <int> subtree;
  function <void(int, int)> get_subtree = [&](int v, int p) {
    subtree.push_back(v);
    for (int to : g[v]) {
      if (to == p || used[to]) {
        continue;
      }
      get_subtree(to, v);
    }
  };
  int root = 1;
  while (n > 1) {
    subtree.clear();
    int centroid = get_centroid(root, par[root]);
    get_subtree(centroid, par[centroid]);
    if (query(subtree)) {
      root = centroid;
      n = sz[root];
    } else {
      used[centroid] = true;
      n -= sz[centroid];
      int cur = centroid;
      while (par[cur] != -1) {
        sz[par[cur]] -= sz[centroid];
        cur = par[cur];
      }
    }
  }
  return root;
}

• Subtask 1: 0 / 40
• Subtask 2: 0 / 40
• Subtask 3: 0 / 20