Submission #878328

#	Time	Username	Problem	Language	Result	Execution time	Memory
878328		Erfan1386Y	Railway (BOI17_railway)	C++14	100 / 100	92 ms	26572 KiB

railway

#include <bits/stdc++.h>
#define file_io freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);
#define fast_io ios::sync_with_stdio(false);cin.tie(0);
#define what(x) cerr << #x << " is " << x << '\n';
#define kill(x) {cout << x << '\n'; return 0;}
#define all(x) (x).begin(), (x).end()
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define ll long long
#define F first
#define S second
const ll inf = 1e18, mod = 1e9 + 7, delta = 1e9 + 9, SQ = 450, P = 6065621;
 
using namespace std;
 
const ll N = 1e5 + 10, LG = 20;
int h[N], par[N][LG], f[N], cnt[N], k, st[N], ft[N], tmp;
vector<pii> adj[N];
vector<int> ans;
 
void pre (int v, int p = -1, int e = -1) {
  par[v][0] = p;
  f[v] = e;
  st[v] = tmp++;
  if (p != -1) h[v] = h[p] + 1;
  for (int i = 1; i < LG; i++) 
    if (par[v][i - 1] != -1) 
      par[v][i] = par[par[v][i - 1]][i - 1];
  for (auto u: adj[v])
    if (p != u.F) 
      pre(u.F, v, u.S);
  ft[v] = tmp;
}
 
int lca (int u, int v) {
  if (h[u] < h[v]) swap(u, v);
  for (int i = LG - 1; i >= 0; i--)
    if (par[u][i] != -1 && h[par[u][i]] >= h[v])
      u = par[u][i];
  if (u == v) return u;
  for (int i = LG - 1; i >= 0; i--)
    if (par[u][i] != par[v][i])
      u = par[u][i], v = par[v][i];
  return par[u][0];
}
 
void dfs (int v, int p = -1) {
  for (auto u: adj[v]) {
    if (u.F != p) {
      dfs(u.F, v);
      if (cnt[u.F] >= 2 * k) {
        ans.pb(u.S);
      }
      cnt[v] += cnt[u.F];
    }
  }
}
 
bool cmp (int i, int j) {
  return st[i] < st[j];
}
 
int main() {
  fast_io;
  int n, m;
  cin >> n >> m >> k;
  memset(par, -1, sizeof par);
  for (int i = 1; i < n; i++) {
    int u, v;
    cin >> u >> v;
    adj[u].pb({v, i});
    adj[v].pb({u, i});
  }
  pre(1);
  for (int i = 1; i <= m; i++) {
    int x;
    cin >> x;
    vector<int> d(x);
    for (int j = 0; j < x; j++)
      cin >> d[j];
    sort(all(d), cmp);
    for (int j = 0; j < x - 1; j++) {
      int v = d[j], u = d[j + 1];
      int l = lca(u, v);
      if (l == v) {
        cnt[u]++;
        cnt[v]--;
        continue;
      }
      else cnt[v]++, cnt[u]++, cnt[l] -= 2;
    }
    int v = d[0], u = d[x - 1];
    int l = lca(u, v);
    if (l == v) {
        cnt[u]++;
        cnt[v]--;
        continue;
      }
    else cnt[v]++, cnt[u]++, cnt[l] -= 2;
  }
  dfs(1);
  // for (int i = 1; i <= n; i++)
  //   cout << cnt[i] << ' ';
  // cout << endl;
  cout << ans.size() << '\n';
  sort(all(ans));
  for (auto u: ans) cout << u << ' ';
  cout << '\n';
  return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 7 / 7
• Subtask 4: 29 / 29
• Subtask 5: 16 / 16
• Subtask 6: 25 / 25