Submission #925489

#	Time	Username	Problem	Language	Result	Execution time	Memory
925489		jcelin	Cat Exercise (JOI23_ho_t4)	C++14	100 / 100	174 ms	58196 KiB

Main

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

typedef long long ll;

typedef pair<int,int> ii;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<ll> vll;
typedef vector<pll> vpll;

#define PB push_back
#define PF push_front
#define PPB pop_back
#define PPF pop_front
#define X first
#define Y second
#define MP make_pair
#define all(x) (x).begin(), (x).end()

const int mod = 1e9 + 7; //998244353;
const int inf = 1e9 + 7;
const ll INF = 1e18 + 7;
const int logo = 18;
const int MAXN = 2e5 + 7;
const int off = 1 << logo;
const int trsz = off << 1;
const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, -1, 1};

struct uf{
	int par[MAXN];
	
	uf(){
		for(int i=1; i<MAXN; i++) par[i] = i;
	}
	
	int find(int x){
		return x == par[x] ? x : par[x] = find(par[x]);
	}
}t;

ll h[MAXN], dp[MAXN], dep[MAXN], par[MAXN][logo];
vi g[MAXN];

int getLCA(int a, int b){
	if(dep[a] < dep[b]) swap(a, b);
	int delta = dep[a] - dep[b];
	for(int i=0; i<logo; i++) if(delta & (1 << i)) a = par[a][i];
	if(a == b) return a;
	for(int i=logo-1; i>=0; i--) if(par[a][i] != par[b][i]) a = par[a][i], b = par[b][i];
	return par[a][0];
}

void dfs(int u, int p = 1){
	dep[u] = dep[p] + 1;
	par[u][0] = p;
	for(auto &x : g[u]) if(x != p) dfs(x, u);
}

int dis(int a, int b){
	return dep[a] + dep[b] - 2 * dep[getLCA(a, b)];
}

void solve(){
	int n;
	cin >> n;
	for(int i=1; i<=n; i++) cin >> h[i];
	
	for(int i=1, a, b; i<n; i++){
		cin >> a >> b;
		g[h[a]].PB(h[b]);
		g[h[b]].PB(h[a]);
	}
	dfs(1);
	for(int j=1; j<logo; j++) for(int i=1; i<=n; i++) par[i][j] = par[par[i][j - 1]][j - 1];
	for(int i=1; i<=n; i++){
		for(auto &x : g[i]){
			if(x > i) continue;
			x = t.find(x);
			dp[i] = max(dp[i], dp[x] + dis(x, i));
			t.par[x] = i;
		}
	}
	cout << dp[n] << "\n";
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int tt = 1;
	//cin >> tt;
	while(tt--) 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