Submission #105539

#	Time	Username	Problem	Language	Result	Execution time	Memory
105539		zscoder	Mergers (JOI19_mergers)	C++17	0 / 100	222 ms	26588 KiB

mergers

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#pragma GCC optimize("unroll-loops,no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

using namespace std;
using namespace __gnu_pbds;
 
#define fi first
#define se second
#define mp make_pair
#define pb push_back
 
typedef long long ll;
typedef pair<ll,ll> ii;
typedef vector<int> vi;
typedef unsigned long long ull;
typedef long double ld; 
typedef tree<ii, null_type, less<ii>, rb_tree_tag, tree_order_statistics_node_update> pbds;

vi adj[555555];
int tot[555555];
int a[555555];
int bad[555555];
int ct;
int act[555555];
int siz[555555];
int par[555555];
void calcsiz(int u, int p=-1)
{
	par[u]=p;
	if(adj[u].size()>1&&adj[u][0]==p) swap(adj[u][1],adj[u][0]);
	siz[u]=1;
	for(auto &v:adj[u])
	{
		if(v==p) continue;
		calcsiz(v,u);
		siz[u]+=siz[v];
		if(siz[v]>siz[adj[u][0]]) swap(v,adj[u][0]);
	}
}

vector<int> V;

void dfs2(int u, int p=-1)
{
	V.pb(a[u]);
	if(act[a[u]]==-1)
	{
		ct++; act[a[u]]=tot[a[u]];
	}
	act[a[u]]--;
	for(int v:adj[u])
	{
		if(v==p) continue;
		dfs2(v,u);
	}
}

void prep(int u, int p=-1)
{
	for(int i=1;i<adj[u].size();i++)
	{
		int v=adj[u][i];
		if(v==p) continue;
		prep(v,u);
		while(!V.empty()){act[V.back()]=-1; V.pop_back();}
		ct=0;
	}
	if(adj[u][0]!=p) prep(adj[u][0],u);
	for(int i=1;i<adj[u].size();i++)
	{
		int v=adj[u][i];
		if(v==p) continue;
		dfs2(v,u);
	}
	if(act[a[u]]==-1)
	{
		ct++; act[a[u]]=tot[a[u]];
	}
	act[a[u]]--;
	V.pb(a[u]);
	if(act[a[u]]==0) ct--;
	if(ct==0) bad[u]=1;
	//if(bad[u]) cerr<<"BAD "<<u<<'\n';
}

set<int> S;

void prep2(int u, int p)
{
	for(int v:adj[u])
	{
		if(v==p) continue;
		prep2(v,u);
	}
	S.insert(a[u]);
}

int dp[555555][2];
const int INF = int(1e9);

void dfs(int u, int p=-1)
{
	vi pre(2,INF);
	pre[0]=0;
	for(int v:adj[u])
	{
		if(v==p) continue;
		dfs(v,u);
		vi nw(2,INF);
		for(int i=0;i<2;i++)
		{
			for(int j=0;j<2;j++)
			{
				if(j==0&&bad[v]) continue;
				if(j==0) nw[i]=min(nw[i],pre[i]+dp[v][j]);
				else nw[i^1]=min(nw[i^1],pre[i]+dp[v][j]+(i==1?-1:0));
				//cerr<<i<<' '<<j<<' '<<nw[0]<<' '<<nw[1]<<'\n';
			}
		}
		pre=nw;
		//cerr<<u<<' '<<pre[0]<<' '<<pre[1]<<'\n';
	}
	dp[u][0]=min(pre[0],pre[1]); dp[u][1]=min(pre[0]+1,pre[1]);
	if(bad[u]) dp[u][0]=INF;
	//cerr<<"DP : "<<u<<' '<<dp[u][0]<<' '<<dp[u][1]<<'\n';
}

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0); 
	int n,k; cin>>n>>k;
	if(n==1){cout<<0<<'\n'; return 0;}
	memset(act,-1,sizeof(act));
	for(int i=0;i<n-1;i++)
	{
		int u,v; cin>>u>>v; u--; v--;
		adj[u].pb(v); adj[v].pb(u);
	}
	for(int i=0;i<n;i++)
	{
		cin>>a[i]; a[i]--;
		tot[a[i]]++;
	}
	calcsiz(0);
	/*
	prep(0); bad[0]=0;
	*/
	for(int i=1;i<n;i++)
	{
		prep2(i,par[i]);
		int sum=0;
		for(int v:S) sum+=tot[v];
		if(siz[i]==sum) 
		{
			bad[i]=1;
			//cerr<<i<<'\n';
		}
		S.clear();
	}
	dfs(0);
	cout<<dp[0][0]<<'\n';
}

Compilation message (stderr)

mergers.cpp: In function 'void prep(int, int)':
mergers.cpp:63:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<adj[u].size();i++)
              ~^~~~~~~~~~~~~~
mergers.cpp:72:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<adj[u].size();i++)
              ~^~~~~~~~~~~~~~

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