제출 #482955

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
482955		PoPularPlusPlus	Mergers (JOI19_mergers)	C++17	100 / 100	1157 ms	177940 KiB

mergers

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long 
#define pb(e) push_back(e)
#define sv(a) sort(a.begin(),a.end())
#define sa(a,n) sort(a,a+n)
#define mp(a,b) make_pair(a,b)
#define vf first
#define vs second
#define ar array
#define all(x) x.begin(),x.end()
const int inf = 0x3f3f3f3f;
const int mod = 1000000007; 
const double PI=3.14159265358979323846264338327950288419716939937510582097494459230;
bool remender(ll a , ll b){return a%b;}

const int N = 500002 , l = 25;
vector<int> adj[N];
int timer;
int tin[N], tout[N];
int up[N][l + 5];
int cnt[N];

void dfs(int v, int p){
    tin[v] = ++timer;
    up[v][0] = p;
    for (int i = 1; i <= l; ++i)
        up[v][i] = up[up[v][i-1]][i-1];

    for (int u : adj[v]) {
        if (u != p)
            dfs(u, v);
    }

    tout[v] = ++timer;
}

bool is_ancestor(int u, int v){
    return tin[u] <= tin[v] && tout[u] >= tout[v];
}

int lca(int u, int v){
    if (is_ancestor(u, v))
        return u;
    if (is_ancestor(v, u))
        return v;
    for (int i = l; i >= 0; --i) {
        if (!is_ancestor(up[u][i], v))
            u = up[u][i];
    }
    return up[u][0];
}

struct UFDS {

int p[N],siz[N];

void init(int n){
	for(int i = 0; i <= n; i++){
		p[i] = i;
		siz[i] = 1;
	}
}

int get(int x){
	return p[x]=(x==p[x] ? x : get(p[x]));
}

void unio(int u , int v){
	int a = get(u);
	int b=get(v);
	if(a==b)return;
	if(siz[a]>siz[b])swap(a,b);
	p[b]=a;
	siz[a]+=siz[b];
}
};

UFDS d;

void dfs1(int node , int par = -1){
	for(int i : adj[node]){
		if(i!=par){
			dfs1(i,node);
			if(cnt[i] != 0)d.unio(i , node);
			cnt[node] += cnt[i];
		}
	}
}

bool cmp(int x , int y){
	return tin[x] < tin[y];
}

void solve(){
	int n;
	cin >> n;
	d.init(n + 2);
	int k;
	cin >> k;
	for(int i = 0; i < n-1; i++){
		int a , b;
		cin >> a >> b;
		adj[a].pb(b);
		adj[b].pb(a);
	}
	vector<int> t[k + 1];
	for(int i = 0; i < n; i++){
		int x;
		cin >> x;
		t[x].pb(i + 1);
	}
	memset(cnt,0,sizeof cnt);
	dfs(1,1);
	for(int i = 1; i <= k; i++){
		sort(all(t[i]),cmp);
		for(int j = 0; j < (int)t[i].size(); j++){
			int lc = lca(t[i][j] , t[i][(j+1)%t[i].size()]);
			cnt[lc]-=2;
			cnt[t[i][j]]++;
			cnt[t[i][(j+1)%t[i].size()]]++;
		}
	}
	dfs1(1,-1);
	vector<int> leaf(n+1,0);
	for(int i = 1; i <= n; i++){
		for(int j : adj[i]){
			if(d.get(i) != d.get(j))leaf[d.get(i)]++,leaf[d.get(j)]++;
		}
	}
	int ans = 0;
	for(int i = 1; i <= n; i++){
		if(leaf[i] == 2)ans++;
	}
	cout << (ans + 1)/2 << '\n';
}

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

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 22 / 22
• Subtask 5: 30 / 30