Submission #312549

#	Time	Username	Problem	Language	Result	Execution time	Memory
312549		model_code	Pastiri (COI20_pastiri)	C++17	100 / 100	860 ms	80200 KiB

pastiri

#include <bits/stdc++.h>
using namespace std;

const int MAXN = 5e5 + 5;

int N, K;
int sheep[MAXN];
int sorted[MAXN];
int cntDep[MAXN];
vector <int> adj[MAXN];
int dep[MAXN], dist[MAXN];
int highest[MAXN];
bool bio[MAXN];

void load() {
  scanf("%d%d", &N, &K);
  for (int i = 1; i < N; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  for (int i = 0; i < K; i++)
    scanf("%d", sheep + i);
}

void dfs_init(int x, int p, int mx, int opt) {
  int sum = dep[x] + dist[x];
  if (sum > mx) {
    mx = sum;
    opt = x;
  }
  highest[x] = opt;
  for (auto it : adj[x])
    if (it != p) {
      dep[it] = dep[x] + 1;
      dfs_init(it, x, mx, opt);
    }
}

void bfs() {
  memset(dist, -1, sizeof dist);
  queue <int> Q;
  for (int i = 0; i < K; i++) {
    dist[sheep[i]] = 0;
    Q.push(sheep[i]);
  }
  while (!Q.empty()) {
    int curr = Q.front();
    Q.pop();
    for (auto it : adj[curr])
      if (dist[it] == -1) {
        dist[it] = dist[curr] + 1;
        Q.push(it);
      }
  }
}

void dfs_cover(int x) {
  bio[x] = true;
  for (auto it : adj[x])
    if (!bio[it] && dist[x] == dist[it] + 1)
      dfs_cover(it);
}

void sort_by_depth() {
  for (int i = 0; i < K; i++)
    cntDep[dep[sheep[i]] + 1]++;
  for (int i = 1; i <= N; i++)
    cntDep[i] += cntDep[i - 1];
  for (int i = 0; i < K; i++)
    sorted[cntDep[dep[sheep[i]]]++] = sheep[i];
  for (int i = 0; i < K; i++) 
    sheep[i] = sorted[K - i - 1];
}

void solve() {
  bfs();
  dfs_init(1, 0, -1, 0);
  sort_by_depth();
  vector <int> ans;
  for (int i = 0; i < K; i++)
    if (!bio[sheep[i]]) {
      ans.push_back(highest[sheep[i]]);
      dfs_cover(highest[sheep[i]]);
    }
  printf("%d\n", ans.size());
  for (auto it : ans)
    printf("%d ", it);
  puts("");
}

int main() {
  load();
  solve();
  return 0;
}

Compilation message (stderr)

pastiri.cpp: In function 'void solve()':
pastiri.cpp:87:12: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wformat=]
   87 |   printf("%d\n", ans.size());
      |           ~^     ~~~~~~~~~~
      |            |             |
      |            int           std::vector<int>::size_type {aka long unsigned int}
      |           %ld
pastiri.cpp: In function 'void load()':
pastiri.cpp:16:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   16 |   scanf("%d%d", &N, &K);
      |   ~~~~~^~~~~~~~~~~~~~~~
pastiri.cpp:19:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   19 |     scanf("%d%d", &u, &v);
      |     ~~~~~^~~~~~~~~~~~~~~~
pastiri.cpp:24:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   24 |     scanf("%d", sheep + i);
      |     ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 18 / 18
• Subtask 3: 23 / 23
• Subtask 4: 51 / 51