Submission #895445

#	Time	Username	Problem	Language	Result	Execution time	Memory
895445		thunopro	Capital City (JOI20_capital_city)	C++14	100 / 100	178 ms	50368 KiB

capital_city

#include<bits/stdc++.h>
using namespace std ; 
#define ll long long 
#define maxn 200009 
#define fi first 
#define se second 
#define pb push_back 
#define left id<<1 
#define right id<<1|1 
#define re exit(0); 
#define _lower(v,x) lower_bound(v.begin(),v.end(),x)-v.begin()+1  

const int mod = 1e9+7 ; 
const int INF = 1e9 ; 
const int LOG = 18 ; 

typedef vector<int> vi ; 
typedef pair<int,int> pii ; 
typedef vector<ll> vl ; 
typedef vector<pii> vii ; 

void add ( int &a , int b ) 
{
	a += b ;
	if ( a < 0 ) a += mod ; 
	if ( a >= mod ) a -= mod ; 
}

template < typename T > void chkmin ( T &a , T b ) { if ( a > b ) a = b ; } 
template < typename T > void chkmax ( T &a , T b ) { if ( a < b ) a = b ; } 

void rf () 
{
	freopen ("bai1.inp","r",stdin) ; 
//	freopen ("bai1.out","w",stdout) ; 
}

int _pow ( int a , int n ) 
{
	if ( n == 0 ) return 1 ; 
	int res = _pow (a,n/2) ; 
	if ( n % 2 ) return 1ll*res*res%mod*a%mod ; 
	else return 1ll*res*res%mod ; 
}

int n , k ; 
int colour [maxn] , num_colour [maxn] ; 

vi adjList [maxn] ; 
vi _adjList [maxn] ; 
void add_edge ( int u , int v ) 
{
	_adjList [u] . pb (v) ; 
}

int sz [maxn] , bigChild [maxn] , ver [maxn] ; 
int tin [maxn] , tout [maxn] , timeDfs ; 
void dfs ( int u = 1 , int par = 1 ) 
{
	tin [u] = ++ timeDfs ; 
	ver [timeDfs] = u ; 
	sz [u] = 1 ; bigChild [u] = - 1 ; 
	for ( auto v : adjList [u] ) 
	{
		if ( v == par ) continue ; 
		dfs (v,u) ; 
		sz [u] += sz [v] ; 
		if ( bigChild[u] == - 1 || sz[bigChild[u]] < sz [v] ) bigChild [u] = v ; 
	}
	tout [u] = timeDfs ; 
}

int cnt [maxn] ; 

void add_colour ( int x , int y ) 
{
	cnt [x] += y ; 	
}
void dsu_on_tree ( int u = 1 , int par = 1 , bool keep = true ) 
{
	for ( auto v : adjList [u] ) 
	{
		if ( v != par && v != bigChild[u] ) dsu_on_tree (v,u,false) ; 
	}
	if ( bigChild [u] != -1 ) dsu_on_tree (bigChild[u],u,true) ; 
	
	for ( auto v : adjList [u] ) 
	{
		if ( v == par || v == bigChild[u] ) continue ; 
		for ( int i = tin [v] ; i <= tout [v] ; i ++ ) add_colour (colour[ver[i]],1) ; 
	}
	
	add_colour (colour[u],1) ;
	if ( cnt[colour[u]] != num_colour [colour[u]] && u != 1 ) add_edge (colour[u],colour[par]) ; 
	if ( !keep ) 
	{
		for ( int i = tin [u] ; i <= tout [u] ; i ++ ) add_colour (colour[ver[i]],-1) ; 
	}
}

int low [maxn] , num [maxn] ;  
int sz_gr [maxn] , gr [maxn] , num_gr ; stack <int> stk ; 
void tarjan ( int u , int par = -1 )
{
	stk . push (u) ; 
	low [u] = num [u] = ++ timeDfs ; 
	for ( auto v : adjList [u] ) 
	{
		if ( !num[v] ) 
		{
			tarjan (v,u) ; 
			chkmin (low[u],low[v]) ; 
		}
		else chkmin (low[u],num[v]) ; 
	}
	if ( low [u] == num [u] )
	{
		num_gr ++ ; 
		while ( true ) 
		{
			int v = stk.top() ; stk.pop() ; 
			gr [v] = num_gr ; sz_gr [num_gr] ++ ; 
			num [v] = low [v] = INF ; 
			if ( u == v ) break ; 
		}
	}
}

int deg [maxn] ; 
void get_answer () 
{
	timeDfs = 0 ; 	
	for ( int i = 1 ; i <= k ; i ++ ) 
	{
		adjList [i] = _adjList [i] , _adjList [i].clear () ; 
		sort (adjList[i].begin(),adjList[i].end()) ; 
		adjList[i].resize(unique(adjList[i].begin(),adjList[i].end())-adjList[i].begin()) ; 
	}
	for ( int i = 1 ; i <= k ; i ++ ) if ( !num[i] ) tarjan (i) ; 
	for ( int i = 1 ; i <= k ; i ++ ) 
	{
		for ( auto x : adjList [i] ) 
		{
			int u = gr [x] , v = gr [i] ; 
			if ( u != v ) deg [v] ++ ; 
		}
	}
	int res = INF ; 
	for ( int i = 1 ; i <= num_gr ; i ++ ) if ( ! deg [i] ) res = min (res,sz_gr [i]) ; 
	cout << res - 1 ; 
}

int main () 
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);cout.tie(0) ; 
//	rf () ; 
	
	cin >> n >> k ; 
	for ( int i = 1 ; i < n ; i ++ ) 
	{
		int u , v ; cin >> u >> v ; 
		adjList [u] . pb (v) ; 
		adjList [v] . pb (u) ; 
	}
	
	for ( int i = 1 ; i <= n ; i ++ ) cin >> colour [i] , num_colour [colour[i]] ++ ; 
		
	dfs () ; 
	dsu_on_tree () ;
	get_answer () ; 
	
}

Compilation message (stderr)

capital_city.cpp: In function 'void rf()':
capital_city.cpp:34:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |  freopen ("bai1.inp","r",stdin) ;
      |  ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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