Submission #936574

#	Time	Username	Problem	Language	Result	Execution time	Memory
936574		penguin133	Cat Exercise (JOI23_ho_t4)	C++17	100 / 100	511 ms	98900 KiB

Main

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

#define int long long
#define pi pair<int, int>
#define pii pair<int, pi>
#define fi first
#define se second
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

int n, P[200005], back[200050];
struct node{
	int s, e, m, val, pos, lz;
	node *l, *r;
	node(int _s, int _e){
		s = _s, e = _e, m = (s + e) >> 1;
		if(s != e){
			l = new node(s, m), r = new node(m+1, e);
		}
		pos = s, val = lz = 0;
	}
	void prop(){
		if(lz){
			val = lz;
			if(s != e)l->lz = lz, r->lz = lz;
			lz = 0;
		}
	}
	void upd(int a, int b, int c){
		prop();
		if(s == a && b == e)lz = c;
		else{
			if(b <= m)l->upd(a, b, c);
			else if(a > m)r->upd(a, b, c);
			else l->upd(a, m, c), r->upd(m+1, b, c);
			l->prop(), r->prop();
			val = max(l->val, r->val);
			if(l->val >= r->val)pos = l->pos;
			else pos = r->pos;
		}
	}
	pi qry(int a, int b){
		prop();
		if(s == a && b == e)return {val, back[pos]};
		if(b <= m)return l->qry(a, b);
		if(a > m)return r->qry(a, b);
		return max(l->qry(a, m), r->qry(m+1, b));
	}
}*root;

int S[200005], E[200005], dep[200005], p[20][200005];
vector <int> adj[200050];
int cnt = 1;
void dfs(int x, int par, int d){
	S[x] = cnt++;
	p[0][x] = par;
	dep[x] = d;
	for(auto i : adj[x])if(i != par)dfs(i, x, d + 1);
	E[x] = cnt - 1;
}

int lca(int u, int v){
	if(dep[u] > dep[v])swap(u, v);
	int df = dep[v] - dep[u];
	for(int i =0 ; i <= 19; i++)if(df >> i & 1)v = p[i][v];
	if(u == v)return u;
	for(int i = 19; i >=0 ; i--){
		if(p[i][u] != p[i][v])u = p[i][u], v = p[i][v];
	}
	return p[0][u];
}

int grr(int x){
	if(S[x] == E[x])return 0;
	int ans = 0, cur = 0, prv = -1;
	while(1){
		pi tmp = root->qry(S[x], E[x]);
		if(tmp.fi <= 0)break;
		if(prv != -1)cur += dep[tmp.se] + dep[prv] - 2 * dep[lca(prv, tmp.se)];
		prv = tmp.se;
		//cout << x << ' ' << tmp.se << '\n';
		for(auto i : adj[tmp.se]){
			if(S[i] < S[tmp.se])continue;
			pi hah = root->qry(S[i], E[i]);
			if(hah.fi > 0)ans = max(ans, cur + dep[hah.se] - dep[tmp.se] + grr(i));
		}
		root->upd(S[tmp.se], E[tmp.se], -1);
	}
	//cout << x << ' ' << cur << ' ' << ans << '\n';
	ans = max(ans, cur);
	return ans;
}

void solve(){
	cin >> n;
	for(int i = 1; i <= n; i++)cin >> P[i];
	root = new node(1, n);
	for(int i = 1; i < n; i++){
		int a, b; cin >> a >> b;
		adj[a].push_back(b); adj[b].push_back(a);
	}
	dfs(1, -1, 0);
	for(int i = 1; i <= 19; i++)for(int j = 1; j <= n; j++)p[i][j] = p[i-1][p[i-1][j]];
	for(int i = 1; i <= n; i++)root->upd(S[i], S[i], P[i]);
	for(int i = 1; i <= n; i++)back[S[i]] = i;
	cout << grr(1);
}

main(){
	ios::sync_with_stdio(0);cin.tie(0);
	int tc = 1;
	//cin >> tc;
	for(int tc1=1;tc1<=tc;tc1++){
		// cout << "Case #" << tc1 << ": ";
		solve();
	}
}

Compilation message (stderr)

Main.cpp:112:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  112 | main(){
      | ^~~~

• 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