Submission #200890

#	Time	Username	Problem	Language	Result	Execution time	Memory
200890		EntityIT	Mergers (JOI19_mergers)	C++14	0 / 100	89 ms	25824 KiB

mergers

#include<bits/stdc++.h>

using namespace std;

#define all(x) (x).begin(), (x).end()
#define sz(x) ( (int)(x).size() )
using LL = long long;

template<class T>
inline bool asMn(T &a, const T &b) { return a > b ? a = b, true : false; }
template<class T>
inline bool asMx(T &a, const T &b) { return a < b ? a = b, true : false; }

const int inf = 1e9;
mt19937 rng( (uint32_t)chrono::steady_clock::now().time_since_epoch().count() );

int n, k;
vector<vector<int> > gr;

vector<int> be, en, ver;
void dfs(int u, int pr) {
  static int iTime = 0;

  ver[iTime] = u;
  be[u] = iTime++;
  for (int v : gr[u]) if (v != pr) dfs(v, u);
  en[u] = iTime - 1;
}

pair<int, int> operator + (const pair<int, int> &a, const pair<int, int> &b) {
  return { min(a.first, b.first), max(a.second, b.second) };
}

vector<vector<pair<int, int> > > rmq;
pair<int, int> get(int l, int r) {
  int i = __lg(r - l + 1);
  return rmq[i][l] + rmq[i][r - (1 << i) + 1];
}

struct Dsu {
  vector<int> pSet;
  Dsu(int nSet = 0) { pSet.assign(nSet, 0); iota(all(pSet), 0); }
  void reset(int nSet = 0) { pSet.assign(nSet, 0); iota(all(pSet), 0); }

  int findSet(int i) { return i == pSet[i] ? i : pSet[i] = findSet(pSet[i]); }
  void unite(int i, int j) {
    i = findSet(i); j = findSet(j);
    if (i == j) return ;
    pSet[i] = j;
  }
} dsu;

vector<pair<int, int> > edge;
void solve(int u, int pr) {
  for (int v : gr[u]) if (v != pr) {
    auto tmp = get(be[v], en[v]);
    if (be[v] <= tmp.first && tmp.second <= en[v]) edge.emplace_back(u, v);
    else dsu.unite(u, v);
    solve(v, u);
  }
}

int main() {
  ios_base::sync_with_stdio(0); cin.tie(0);

  #ifdef FourLeafClover
  freopen("input", "r", stdin);
  #endif // FourLeafCLover

  cin >> n >> k;
  gr.assign(n, {} );
  for (int i = 1; i < n; ++i) {
    int u, v; cin >> u >> v; --u; --v;
    gr[u].emplace_back(v);
    gr[v].emplace_back(u);
  }

  be.assign(n, 0);
  en.assign(n, 0);
  ver.assign(n, 0);
  dfs(0, -1);

  vector<int> s(n), L(k, inf), R(k, -inf);
  for (int u = 0; u < n; ++u) {
    cin >> s[u]; --s[u];
    asMn(L[ s[u] ], be[u]);
    asMx(R[ s[u] ], be[u]);
  }

  rmq.assign(__lg(n) + 1, vector<pair<int, int> >(n, { 0, 0 } ) );
  for (int u = 0; u < n; ++u) rmq[0][ be[u] ] = { L[ s[u] ], R[ s[u] ] };
  for (int j = 1; j < sz(rmq); ++j) {
    for (int i = 0; i + (1 << j) <= n; ++i) rmq[j][i] = rmq[j - 1][i] + rmq[j - 1][i + (1 << (j - 1) )];
  }

  dsu.reset(n);

  solve(0, -1);

  vector<int> cnt(n);
  for (auto e : edge) {
    ++cnt[ dsu.findSet(e.first) ];
    ++cnt[ dsu.findSet(e.second) ];
  }

  cout << max(0, (int)(count(all(cnt), 1) ) - 1) << '\n';

  return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 24
• Subtask 3: 0 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30