Submission #563757

#	Time	Username	Problem	Language	Result	Execution time	Memory
563757		errorgorn	Mergers (JOI19_mergers)	C++17	100 / 100	957 ms	107320 KiB

mergers

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

#define int long long
#define ii pair<int,int>
#define fi first
#define se second
#define endl '\n'

#define puf push_front
#define pof pop_front
#define pub push_back
#define pob pop_back
#define lb lower_bound
#define ub upper_bound

#define rep(x,s,e) for (int x=(s)-((s)>(e));x!=(e)-((s)>(e));((s)<(e)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int) (x).size()

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

struct UFDS{
	int p[500005];
	
	UFDS(){
		rep(x,0,500005) p[x]=x;
	}
	
	int par(int i){
		if (p[i]==i) return p[i];
		else return p[i]=par(p[i]);
	}
	
	void unions(int i,int j){
		i=par(i),j=par(j);
		p[j]=i;
	}
} ufds;

int n,k;
vector<int> al[500005];
vector<ii> edges;
vector<int> pos[500005];

int d[500005];
int pp[500005];

void dfs(int i,int p){
	for (auto it:al[i]){
		if (it==p) continue;
		
		d[it]=d[i]+1;
		pp[it]=i;
		
		dfs(it,i);
	}
}

int deg[500005];

signed main(){
	cin>>n>>k;
	
	int a,b;
	rep(x,1,n){
		cin>>a>>b;
		al[a].pub(b);
		al[b].pub(a);
		edges.pub({a,b});
	}
	
	rep(x,1,n+1){
		cin>>a;
		pos[a].pub(x);
	}
	
	dfs(1,-1);
	
	rep(x,1,k+1) rep(y,1,sz(pos[x])){
		int a=pos[x][0],b=pos[x][y];
		//cout<<a<<" "<<b<<endl;
		
		while (a!=b){
			if (d[a]<d[b]) swap(a,b);
			ufds.unions(pp[a],a);
			a=ufds.par(a);
		}
	}
	
	for (auto [a,b]:edges){
		a=ufds.par(a),b=ufds.par(b);
		if (a!=b) deg[a]++,deg[b]++;
	}
	
	int ans=0;
	rep(x,1,n+1) ans+=deg[x]==1;
	
	cout<<(ans+1)/2<<endl;
}

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