Submission #832160

#	Time	Username	Problem	Language	Result	Execution time	Memory
832160		arush_agu	Mergers (JOI19_mergers)	C++17	70 / 100	637 ms	262144 KiB

mergers

#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#ifdef DEBUG
#include <time.h>
#endif

#define all(a) (a).begin(), (a).end()
#define rev(a) (a).rbegin(), (a).rend()
#define F first
#define S second
int recur_depth = 0;
#ifdef DEBUG
#define dbg(x)                                                                 \
  {                                                                            \
    ++recur_depth;                                                             \
    auto x_ = x;                                                               \
    --recur_depth;                                                             \
    cerr << string(recur_depth, '\t') << "\e[91m" << __func__ << ":"           \
         << __LINE__ << "\t" << #x << " = " << x_ << "\e[39m" << endl;         \
  }
#else
#define dbg(x)
#endif

using namespace std;
using namespace __gnu_pbds;

typedef pair<int, int> ii;

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> llll;

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pair<int, int>> vii;
typedef vector<vii> vvii;

typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pair<ll, ll>> vll;
typedef vector<vll> vvll;

typedef vector<bool> vb;

template <class type1>
using ordered_set = tree<type1, null_type, less<type1>, rb_tree_tag,
                         tree_order_statistics_node_update>;

template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &p) {
  return os << '(' << p.first << ", " << p.second << ')';
}
template <typename T_container, typename T = typename enable_if<
                                    !is_same<T_container, string>::value,
                                    typename T_container::value_type>::type>
ostream &operator<<(ostream &os, const T_container &v) {
  os << '{';
  string sep;
  for (const T &x : v)
    os << sep << x, sep = ", ";
  return os << '}';
}

const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
const ll INF = 1e9;
const ld EPS = 1e-9;

struct ST {
  const int MAXLG = 22;
  int n;
  vi lg2;
  vvii st;

  ST(vii &a) : n(a.size()) {
    st = vvii(MAXLG, vii(n));
    st[0] = a;
    for (int j = 1; j < MAXLG; j++)
      for (int i = 0; i + (1 << j) <= n; i++)
        st[j][i] = min(st[j - 1][i], st[j - 1][i + (1 << (j - 1))]);

    lg2 = vi(n + 1);
    lg2[1] = 0;
    for (int i = 2; i <= n; i++)
      lg2[i] = lg2[i / 2] + 1;
  }

  int query(int l, int r) {
    if (l > r)
      swap(l, r);
    int k = lg2[r - l + 1];
    return min(st[k][l], st[k][r - (1 << k) + 1]).second;
  }
};

void solve() {
  int n, k;
  cin >> n >> k;
  vvi adj(n);
  for (int i = 0; i < n - 1; i++) {
    int u, v;
    cin >> u >> v;
    u--, v--;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  vi st(n);
  for (int &x : st)
    cin >> x, x--;

  int timer = 0;
  vi par(n, -1), depth(n), first_occ(n, -1), tin(n), tout(n);
  vii euler;
  function<void(int, int)> f = [&](int u, int p) {
    tin[u] = timer++;
    first_occ[u] = euler.size();
    euler.push_back({depth[u], u});
    for (int &v : adj[u])
      if (v != p) {
        par[v] = u;
        depth[v] = depth[u] + 1;
        f(v, u);
        euler.push_back({depth[u], u});
      }
    tout[u] = timer++;
  };
  f(0, -1);
  ST lc(euler);

  vvi by_state(k);
  for (int i = 0; i < n; i++)
    by_state[st[i]].push_back(i);

  vl b(n);
  for (int i = 0; i < k; i++) {
    int lca = by_state[i][0];
    for (int &u : by_state[i])
      lca = lc.query(first_occ[lca], first_occ[u]);
    b[lca] += by_state[i].size();
  }

  int cc = 0;
  vl sub_sz(n);
  function<void(int, int)> g = [&](int u, int p) {
    sub_sz[u] = 1;
    for (int &v : adj[u])
      if (v != p) {
        g(v, u);
        sub_sz[u] += sub_sz[v];
      }
    sub_sz[u] -= b[u];
    if (!sub_sz[u])
      cc++;
  };
  g(0, -1);

  if (cc == 1) {
    cout << "0\n";
    return;
  }

  vl cnt(n);
  int no_leaves = 0;
  function<void(int, int, int)> h = [&](int u, int p, int curr) {
    if (sub_sz[u] == 0 && curr != u)
      cnt[u]++, cnt[curr]++, curr = u;
    for (int &v : adj[u])
      if (v != p)
        h(v, u, curr);
    if (cnt[u] == 1)
      no_leaves++;
  };

  h(0, -1, 0);
  cout << (no_leaves + 1) / 2 << '\n';
}

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

  clock_t start = clock();

  int test_cases = 1;
  // cin >> test_cases;

  while (test_cases--)
    solve();

#ifdef DEBUG
  cerr << fixed << setprecision(10)
       << "\nTime Taken: " << (double)(clock() - start) / CLOCKS_PER_SEC
       << "s\n";
#endif
  return 0;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:205:11: warning: unused variable 'start' [-Wunused-variable]
  205 |   clock_t start = clock();
      |           ^~~~~

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