Submission #1160531

#	Time	Username	Problem	Language	Result	Execution time	Memory
1160531		fryingduc	Cat Exercise (JOI23_ho_t4)	C++20	0 / 100	3 ms	4932 KiB

Main

#include "bits/stdc++.h"

using namespace std;

#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif

const int maxn = 2e5 + 5;
const int LG = 18;
int n;
vector<int> g[maxn];
int p[maxn], rev[maxn];
int h[maxn], up[maxn][LG + 1], f[maxn];

void dfs(int u, int prev) {
  for (auto v:g[u]) {
    if (v == prev) continue;
    h[v] = h[u] + 1;
    up[v][0] = u;
    for (int i = 1; i <= LG; ++i) {
      up[v][i] = up[up[v][i - 1]][i - 1];
    }
    dfs(v, u);
  }
}

int lca(int u, int v) {
  if (h[u] < h[v]) swap(u, v);
  for (int i = LG; i >= 0; --i) {
    if ((h[u] - h[v]) >> i & 1) {
      u = up[u][i];
    }
  }
  if (u == v) return u;
  for (int i = LG; i >= 0; --i) {
    if (up[u][i] != up[v][i]) {
      u = up[u][i], v = up[v][i];
    }
  }
  return up[u][0];
}

int dist(int u, int v) {
  return h[u] + h[v] - 2 * h[lca(u, v)];
}

int lab[maxn];

int find(int u) {
  return lab[u] < 0 ? u : lab[u] = find(lab[u]);
}

void solve() {
  cin >> n;
  for (int i = 1; i <= n; ++i) {
    cin >> p[i];
    rev[p[i]] = i;
    lab[i] = -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, 0);
  for (int i = 1; i <= n; ++i) {
    int u = rev[i];
    for (auto v:g[u]) {
      if (p[v] < i) {
        v = find(v);
        f[u] = max(f[u], f[v] + dist(u, v));
      }
    }
    for (auto v:g[u]) {
      if (p[v] < i) {
        lab[find(v)] = u;
      }
    }
  }
  cout << f[n];
}

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

  solve();

  return 0;
}

• Subtask 1: 0 / 7
• Subtask 2: 0 / 7
• Subtask 3: 0 / 7
• Subtask 4: 0 / 10
• Subtask 5: 0 / 20
• Subtask 6: 0 / 23
• Subtask 7: 0 / 26