제출 #938825

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
938825		THXuan	Cat Exercise (JOI23_ho_t4)	C++14	100 / 100	378 ms	122604 KiB

Main

#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#define INF 1e18
using namespace std;
typedef long long ll;

vector<int>adj[2000005];
ll d[2000005],par[2000005], p[2000005][25], dp[2000005];

void dfs(int s, int e) {
	for (int i = 1; i <=20; i++) {
		p[s][i] = p[p[s][i - 1]][i - 1];
	}
	for (auto u : adj[s]) {
		if (u == e) continue;
		d[u] = d[s] + 1;
		p[u][0] = s;
		dfs(u, s);
	}
}

int lca(int a, int b) {
	if (d[a] > d[b]) swap(a, b);
	int dist = d[b] - d[a];
	for (int i = 0; i <= 20; i++) {
		if (dist & (1 << i))b = p[b][i];
	}
	if (a == b) return a;
	for (int i = 20; i >= 0; i--) {
		if (p[a][i] != p[b][i]) {
			a = p[a][i];
			b = p[b][i];
		}
	}
	return p[a][0];
}

int find(int x) {
	while (x != par[x])x = par[x];
	return x;
}

int get_dist(int a, int b) {
	int lcaa = lca(a, b);
	return (d[a] - d[lcaa]) + (d[b] - d[lcaa]);
}

void solve()
{
	int n; cin >> n;
	vector<int>v(n + 1);
	for (int i = 1; i <= n; i++) cin >> v[i];
	for (int i = 1; i <= n - 1; i++) {
		int a, b; cin >> a >> b;
		a = v[a]; b = v[b];
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	dfs(1, 0);
	for (int i = 1; i <= n; i++) par[i] = i;
	for (int i = 1; i <= n; i++) {
		for (auto u : adj[i]) {
			u = find(u);
			if (u < i) {
				par[u] = i;
				dp[i] = max(dp[i], dp[u] + get_dist(i, u));
			}
		}
	}
	cout << dp[n] << "\n";
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int t = 1;// cin>>t;
	while (t--) solve();
	return 0;
}

• 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