Submission #365800

#	Time	Username	Problem	Language	Result	Execution time	Memory
365800		negar_a	Capital City (JOI20_capital_city)	C++14	1 / 100	1010 ms	38120 KiB

capital_city

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

typedef long long ll;
typedef long double ld;
#define pb push_back
#define mp make_pair
#define pii pair <int, int>
#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define F first
#define S second

const int maxn = 2e5 + 5;
vector <int> adj[maxn], vec[maxn];
int sz[maxn], par[maxn], c[maxn];
int ans;
bool cent[maxn], mark[maxn], com[maxn], visit[maxn];

void dfs(int v, int p = -1){
	sz[v] = 1;
	com[v] = true;
	for(int u : adj[v]){
		if(!cent[u] && u != p){
			dfs(u, v);
			sz[v] += sz[u];
		}
	}
}
int find_centroid(int v, int s, int p = -1){
	for(int u : adj[v]){
		if(!cent[u] && u != p && sz[u] > s / 2){
			return find_centroid(u, s, v);
		}
	}
	return v;
}
void dfs2(int v, int p = -1){
	for(int u : adj[v]){
		if(!cent[u] && u != p){
			par[u] = v;
			dfs2(u, v);
		}
	}
}
void clean(int v, int p = -1){
	com[v] = false;
	par[v] = 0;
	sz[v] = 0;
	for(int u : adj[v]){
		if(u != p && !cent[u])
			clean(u, v);
	}
}

void solve(int v){
	dfs(v);
	int cn = find_centroid(v, sz[v]);
//	cout << "cen : " << cn << endl; 
	
	par[cn] = -1;
	dfs2(cn);
	
	queue <int> q;
	vector <int> vc;
	
	q.push(c[cn]);
	bool flag = true; 
	mark[c[cn]] = true;
	while(q.size() && flag){
		int x = q.front();
		q.pop();
		vc.pb(x);
		if(visit[x])
			flag = false;
		for(int u : vec[x]){
			if(!com[u]){
				flag = false;
				break;
			}
			if(par[u] != -1 && !mark[c[par[u]]]){
				if(!com[par[u]]){
					flag = false;
					break;
				}
				q.push(c[par[u]]);
				mark[c[par[u]]] = true;
			}
		}
	}
	visit[c[cn]] = true;
	if(flag){
		ans = min(ans, (int)vc.size() - 1);
	}
		
	//clear
	for(int u : vc)
		mark[u] = false;
	clean(v);
		
	cent[cn] = true;
	for(int u : adj[cn]){
		if(!cent[u]){
			solve(u);
		}
	}
}

int main(){
	fast_io;
	int n, k;
	cin >> n >> k;
	for(int i = 0; i < n - 1; i ++){
		int x, y;
		cin >> x >> y;
		x --; y --;
		adj[x].pb(y);
		adj[y].pb(x);
	}
	for(int i = 0; i < n; i ++){
		cin >> c[i];
		vec[c[i]].pb(i);
	}
	ans = k - 1;
	solve(0);
	cout << ans;
	
	return 0;
}
/*
6 3
2 1
3 5
6 2
3 4
2 3
1 3 1 2 3 2

8 4
4 1
1 3
3 6
6 7
7 2
2 5
5 8
2 4 3 1 1 2 3 4

12 4
7 9
1 3
4 6
2 4
10 12
1 2
2 10
11 1
2 8
5 3
6 7
3 1 1 2 4 3 3 2 2 3 4 4
*/

• Subtask 1: 1 / 1
• Subtask 2: 0 / 10
• Subtask 3: 0 / 30
• Subtask 4: 0 / 59