Submission #1114238

#	Time	Username	Problem	Language	Result	Execution time	Memory
1114238		Dan4Life	Mergers (JOI19_mergers)	C++17	34 / 100	3100 ms	52976 KiB

mergers

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) begin(a),end(a)
 
using ar2 = array<int,2>;
const int N = (int)5e5+10;
int n, k;
int p[N], sz[N];
int a[N], tot[N], cnt[N], deg[N];
vector<int> v[N], adj[N];
 
int findSet(int i){return i==p[i]?i:p[i]=findSet(p[i]);}
void unionSet(int i, int j){
	int x = findSet(i), y = findSet(j);
	if(x==y) return;
	if(sz[x]<sz[y])swap(x,y);
	p[y] = x, sz[x]+=sz[y];
}
 
void dfs(int s, int p){
	v[s].pb(a[s]);
	for(auto u : adj[s]){
		if(u==p) continue;
		dfs(u,s);
		if(sz(v[s]) < sz(v[u])) v[s].swap(v[u]);
		for(auto w : v[u]) v[s].pb(w);
		v[u].clear();v[u].shrink_to_fit();
	}
	int ok = 1;
	for(auto u : v[s]) cnt[u]++;
	for(auto u : v[s]){
		ok&=(cnt[u]==tot[u]);
		if(!ok) break;
	}
	for(auto u : v[s]) cnt[u]--;
	if(p and !ok) unionSet(s,p);
}
 
int32_t main(){
	ios_base::sync_with_stdio(false); cin.tie(0);
	cin >> n >> k;
	for(int i = 1; i <= n; i++) p[i]=i,sz[i]=1;
	for(int i = 1; i < n; i++){
		int a, b; cin >> a >> b;
		adj[a].pb(b); adj[b].pb(a);
	}
	for(int i = 1; i <= n; i++)
		cin >> a[i], tot[a[i]]++;
	dfs(1,0);
	for(int i = 1; i <= n; i++){
		int x = findSet(i);
		for(int j : adj[i])
			deg[x]+=(x!=findSet(j));
	}
	int cnt = 1;
	for(int i = 1; i <= n; i++) cnt+=(deg[i]==1);
	cout << cnt/2 << "\n";
}

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 0 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30