제출 #786975

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
786975		tch1cherin	Cat Exercise (JOI23_ho_t4)	C++17	100 / 100	301 ms	46336 KiB

Main

#include <bits/stdc++.h>
using namespace std;

const int MAX_N = 2e5 + 5, MAX_LOG = 18;
vector<int> G[MAX_N];
int ancestor[MAX_LOG][MAX_N] = {}, depth[MAX_N] = {};

void DFS(int current, int parent) {
  ancestor[0][current] = parent;
  for (int step = 0; step < MAX_LOG - 1; step++) {
    ancestor[step + 1][current] = ancestor[step][ancestor[step][current]];
  }  
  for (int child : G[current]) {
    if (child != parent) {
      depth[child] = depth[current] + 1;
      DFS(child, current);
    }
  }
}

int distance(int u, int v) {
  if (depth[u] < depth[v]) {
    swap(u, v);
  }
  int answer = depth[u] - depth[v];
  for (int step = MAX_LOG - 1; step >= 0; step--) {
    if (depth[u] - (1 << step) >= depth[v]) {
      u = ancestor[step][u];
    }
  }
  if (u == v) {
    return answer;
  }
  for (int step = MAX_LOG - 1; step >= 0; step--) {
    if (ancestor[step][u] != ancestor[step][v]) {
      u = ancestor[step][u];
      v = ancestor[step][v];
      answer += 2 * (1 << step);
    }
  }
  answer += 2;
  return answer;
}

struct dsu {
  vector<int> parent;

  dsu(int size) : parent(size, -1) {}

  int leader(int u) {
    if (parent[u] == -1) {
      return u;
    } else {
      parent[u] = leader(parent[u]);
      return parent[u];
    }
  }

  void unite(int u, int v) {
    u = leader(u);
    v = leader(v);
    if (u != v) {
      if (u < v) {
        swap(u, v);
      }
      parent[v] = u;
    }
  }
};

int main() {
  int N;
  cin >> N;
  vector<int> P(N);
  for (int i = 0; i < N; i++) {
    cin >> P[i];
    P[i]--;
  }
  vector<int> position(N);
  for (int i = 0; i < N; i++) {
    position[P[i]] = i;
  }
  for (int i = 0; i < N - 1; i++) {
    int A, B;
    cin >> A >> B;
    A--, B--;
    G[P[A]].push_back(P[B]);
    G[P[B]].push_back(P[A]); 
  }
  DFS(0, 0);
  dsu sets(N);
  vector<long long> component_result(N);
  for (int i = 0; i < N; i++) {
    for (int j : G[i]) {
      if (j < i) {
        j = sets.leader(j);
        component_result[i] = max(component_result[i], component_result[j] + distance(i, j));
        sets.unite(i, j);
      }
    }
  }
  cout << component_result[N - 1] << "\n";
}

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 10 / 10
• Subtask 5: 20 / 20
• Subtask 6: 23 / 23
• Subtask 7: 26 / 26