Submission #832182

#	Time	Username	Problem	Language	Result	Execution time	Memory
832182		arush_agu	Mergers (JOI19_mergers)	C++17	100 / 100	949 ms	141380 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;

const int MAXN = 5e5 + 1;
const int MAXLG = 22;

int in[MAXN], out[MAXN];
int timer = 0;
int p[MAXN][MAXLG];
vvi g(MAXN);
void dfs(int v, int e) {
  in[v] = timer++;
  p[v][0] = e;
  for (int j = 1; j <= 20; j++)
    p[v][j] = p[p[v][j - 1]][j - 1];
  for (int to : g[v]) {
    if (to == e)
      continue;
    dfs(to, v);
  }
  out[v] = timer++;
}

bool isancestor(int u, int v) { return in[u] <= in[v] && out[u] >= out[v]; }

int lca(int u, int v) {
  if (isancestor(u, v))
    return u;
  if (isancestor(v, u))
    return v;
  for (int j = 20; j >= 0; j--) {
    if (!isancestor(p[u][j], v))
      u = p[u][j];
  }
  return p[u][0];
}

vi sz(MAXN), a(MAXN);
int c = 0;
void dfs2(int v, int e) {
  sz[v] = 1;
  for (int to : g[v]) {
    if (to == e)
      continue;
    dfs2(to, v);
    sz[v] += sz[to];
  }
  sz[v] -= a[v];
  if (sz[v] == 0)
    c++;
}

int cnt[MAXN];
int leaf = 0;
void ansdfs(int v, int cur, int e) {
  if (sz[v] == 0 && cur != v)
    cnt[v]++, cnt[cur]++;
  if (sz[v] == 0)
    cur = v;
  for (int to : g[v]) {
    if (to != e)
      ansdfs(to, cur, v);
  }
  if (cnt[v] == 1)
    leaf++;
}

void solve() {
  int n;
  cin >> n;
  int k;
  cin >> k;
  vector<vector<int>> vec(k + 1);
  for (int i = 1; i < n; i++) {
    int u, v;
    cin >> u >> v;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  dfs(1, 1);
  for (int i = 1; i <= n; ++i) {
    int x;
    cin >> x;
    vec[x].push_back(i);
  }

  for (int i = 1; i <= k; i++) {
    if (vec[i].empty())
      continue;
    int lc = vec[i][0];
    for (int to : vec[i])
      lc = lca(lc, to);
    a[lc] += vec[i].size();
  }
  dfs2(1, 1);
  if (c == 1)
    cout << 0 << "\n";
  else {
    ansdfs(1, 1, 1);
    cout << (leaf + 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:196:11: warning: unused variable 'start' [-Wunused-variable]
  196 |   clock_t start = clock();
      |           ^~~~~

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