Submission #1102498

#	Time	Username	Problem	Language	Result	Execution time	Memory
1102498		hqminhuwu	Cat Exercise (JOI23_ho_t4)	C++14	100 / 100	175 ms	81316 KiB

Main

#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair <ll,ll> pll;
typedef pair <int,int> pii;
typedef pair <int,pii> piii;

#define forr(_a,_b,_c) for(int _a = (_b); _a <= int (_c); ++_a)
#define ford(_a,_b,_c) for(int _a = (_b) + 1; _a --> int (_c);)
#define forf(_a,_b,_c) for(int _a = (_b); _a < int (_c); ++_a)
#define st first
#define nd second
#define pb push_back
#define mp make_pair
#define all(x) begin(x),end(x)
#define mask(i) (1LL << (i))
#define bit(x, i) (((x) >> (i)) & 1)
#define bp __builtin_popcountll
#define file "test"

template<class X, class Y>
	bool minz(X &x, const Y &y) {
		if (x > y) {
			x = y;
			return true;
		} return false;
	}
template<class X, class Y>
	bool maxz(X &x, const Y &y) {
		if (x < y) {
			x = y;
			return true;
		} return false;
	}

const int N = 5e5 + 5;
const ll oo = (ll) 1e16;
const ll mod = 1e9 + 7; // 998244353;

int dep[N], up[20][N], par[N], sz[N], mx[N], a[N], u, v, n;
ll dp[N];
vector <int> g[N];

void dfs(int u){
	for (int v : g[u]){
		if (dep[v]) continue;
		dep[v] = dep[u] + 1;
		up[0][v] = u;
		forr (i, 1, 17)
			up[i][v] = up[i - 1][up[i - 1][v]]; 
		dfs(v);
	}
}

int lca (int u, int v){
	if (dep[u] < dep[v]) swap(u, v);
	
	int k = dep[u] - dep[v];
	ford (i, 17, 0)
	if (bit(k, i))
		u = up[i][u];

	if (u == v){
		return u;
	}

	ford (i, 17, 0)
	if (up[i][u] != up[i][v]){
		u = up[i][u];
		v = up[i][v];
	}

	return up[0][u];
}

int get (int u){
	return u == par[u] ? u : par[u] = get(par[u]);
}

bool update (int u, int v){
	u = get(u); v = get(v);
	if (u == v) return 0;
	
	if (sz[u] < sz[v]) swap(u, v);
	par[v] = u;
	sz[u] += sz[v];
	maxz(mx[u], mx[v]);
	return 1;
}

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

int main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	#ifdef kaguya
		freopen(file".inp", "r", stdin); freopen(file".out", "w", stdout);
	#endif

	cin >> n;

	forr (i, 1, n){
		cin >> a[i];
		sz[i] = 1;
		par[i] = i;
		mx[i] = i; 
	}

	forf (i, 1, n){
		cin >> u >> v;
		g[a[u]].pb(a[v]);
		g[a[v]].pb(a[u]);
	}

	dep[1] = 1;
	dfs(1);	

	forr (i, 1, n){
		for (int v : g[i])
		if (v < i){
			int k = mx[get(v)];
			maxz(dp[i], dp[k] + dis(i, k));
			update(i, v);
		}
	}

	cout << dp[n] << "\n";

	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