Submission #538566

#	Time	Username	Problem	Language	Result	Execution time	Memory
538566		Soumya1	Mergers (JOI19_mergers)	C++17	0 / 100	96 ms	32120 KiB

mergers

#include <bits/stdc++.h>
#ifdef __LOCAL__
#include <debug_local.h>
#endif
using namespace std;
const int mxN = 5e5 + 5;
const int lg = 20;
vector<int> ad[mxN];
int c[mxN];
int p[mxN][lg];
int d[mxN];
int mn[mxN];
int f[mxN];
int leafs = 0;
int comps = 0;
void dfs(int u) {
  for (int i = 1; i < lg; i++) {
    p[u][i] = p[p[u][i - 1]][i - 1];
  }
  for (int v : ad[u]) {
    if (v == p[u][0]) continue;
    p[v][0] = u;
    d[v] = d[u] + 1;
    dfs(v);
  }
}
int lca(int u, int v) {
  if (d[u] < d[v]) swap(u, v);
  for (int j = 0; j < lg; j++) {
    if ((d[u] - d[v]) & (1 << j)) {
      u = p[u][j];
    }
  }
  if (u == v) return u;
  for (int i = lg - 1; i >= 0; i--) {
    if (p[u][i] != p[v][i]) {
      u = p[u][i];
      v = p[v][i];
    }
  }
  return p[u][0];
}
void decompose(int u) {
  for (int v : ad[u]) {
    if (v == p[u][0]) continue;
    decompose(v);
    mn[u] = min(mn[u], mn[v]);
    f[u] += f[v];
  }
  if (mn[u] == d[u]) {
    comps++;
    if (f[u] == 0) leafs++;
    f[u] = 1;
  }
}
void testCase() {
  int n, k;
  cin >> n >> k;
  for (int i = 1; i < n; i++) {
    int u, v;
    cin >> u >> v;
    ad[u].push_back(v);
    ad[v].push_back(u);
  }
  for (int i = 1; i <= n; i++) cin >> c[i];
  dfs(1);
  {
    vector<int> nodes[k + 1];
    for (int i = 1; i <= n; i++) {
      mn[i] = d[i];
      nodes[c[i]].push_back(i);
    }
    for (int i = 1; i <= k; i++) {
      int l = nodes[i][0];
      for (int j : nodes[i]) {
        l = lca(l, j);
      }
      for (int j : nodes[i]) {
        mn[j] = min(mn[j], d[l]);
      }
    }
  }
  decompose(1);
  if (comps == 1) leafs--;
  cout << (leafs + 1) / 2 << "\n";
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  testCase();
  return 0;
}

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