Submission #1125121

#	Time	Username	Problem	Language	Result	Execution time	Memory
1125121		pan	Cat Exercise (JOI23_ho_t4)	C++20	100 / 100	488 ms	72200 KiB

Main

#include <bits/stdc++.h>
//#include "includeall.h"
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
#define endl '\n'
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define lb lower_bound
#define ub upper_bound
#define input(x) scanf("%lld", &x);
#define input2(x, y) scanf("%lld%lld", &x, &y);
#define input3(x, y, z) scanf("%lld%lld%lld", &x, &y, &z);
#define input4(x, y, z, a) scanf("%lld%lld%lld%lld", &x, &y, &z, &a);
#define print(x, y) printf("%lld%c", x, y);
#define show(x) cerr << #x << " is " << x << endl;
#define show2(x,y) cerr << #x << " is " << x << " " << #y << " is " << y << endl;
#define show3(x,y,z) cerr << #x << " is " << x << " " << #y << " is " << y << " " << #z << " is " << z << endl;
#define all(x) x.begin(), x.end()
#define discretize(x) sort(x.begin(), x.end()); x.erase(unique(x.begin(), x.end()), x.end());
#define FOR(i, x, n) for (ll i =x; i<=n; ++i) 
#define RFOR(i, x, n) for (ll i =x; i>=n; --i) 
using namespace std;
//using namespace __gnu_pbds;
//#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
//#define ordered_multiset tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>
typedef long long ll;
//typedef __int128 ull;
typedef long double ld;
typedef pair<ld, ll> pd;
typedef pair<string, ll> psl;
typedef pair<ll, ll> pi;
typedef pair<pi, ll> pii;
typedef pair<pi, pi> piii;

// General
ll n, u, v, ans = 0;
ll p[200005], r[200005];

// 2-k decomposition

vector<ll> adj[200005];
ll dist[200005];
ll twok[200005][20];

void dfs(ll x= 1, ll p = -1)
{
	for (ll k=1; k<20; ++k)
	{
		if (twok[x][k-1]==-1) twok[x][k] = -1;
		else twok[x][k] = twok[twok[x][k-1]][k-1];
	}
	for (ll u: adj[x]) if (u!=p) 
	{
		dist[u] = dist[x] + 1;
		twok[u][0] = x;
		dfs(u, x);
	}
}

ll lca(ll a, ll b)
{
	if (a==b) return a;
	if (dist[a]< dist[b]) swap(a, b);
	for (ll k=19; k>=0; --k) if ((dist[a] - dist[b]) & (1LL << k)) a = twok[a][k];
	if (a==b) return a;
	for (ll k=19; k>=0; --k)
	{
		if (twok[a][k]==twok[b][k]) continue;
		a = twok[a][k], b = twok[b][k];
	}
	return twok[a][0];
}

ll sp(ll a, ll b)
{
	return dist[a] + dist[b] - 2*dist[lca(a, b)];
}

// UFDS Tree
vector<ll> adj2[200005];
ll par[200005];
ll find(ll x) {return (par[x]==x)?x:par[x] = find(par[x]);}
void unite(ll x, ll y)
{
	x = find(x), y = find(y);
	if (x==y) return;
	if (p[x] > p[y]) swap(x, y);
	par[x] = y;
	adj2[y].pb(x);
}


void dfs2(ll x, ll v = 0)
{
	//show2(x, v);
	ans = max(ans, v);
	for (ll u: adj2[x]) dfs2(u, v + sp(x, u));
}
int main()
{
	cin >> n;
	for (ll i=1; i<=n; ++i) {cin >> p[i]; r[p[i]] = i;}
	for (ll i=0; i<n-1; ++i)
	{
		cin >> u >> v;
		adj[u].pb(v);
		adj[v].pb(u);
	}
	dist[1] = 0;
	twok[1][0] = -1;
	dfs();
	for (ll i=1; i<=n; ++i) par[i] = i;
	for (ll i=1; i<=n; ++i) for (ll u: adj[r[i]]) {if (p[u] < i) unite(u, r[i]);}
	//for (ll i=1; i<=n; ++i) {show(i) ; for (ll u: adj2[i]) show(u);}
	dfs2(r[n]);
	cout << ans << endl;
	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