This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
const int mxn=2e5+5;
const int inf=1e9;
const int B=20;
vector<int> adj[mxn];
vector<int> adj2[mxn*B],adjr[mxn*B];
bool visited[mxn*B];
int c[mxn];
int up[mxn][B];
int id[mxn][B];
int depth[mxn];
vector<int> belong[mxn];
vector<int> ord;
int L[mxn];
int sz[mxn*B];
int scc[mxn*B];
int out[mxn*B];
int n,k;
void dfs(int v,int p=0){
up[v][0]=p;
depth[v]=depth[p]+1;
for(auto u:adj[v]){
if(u==p) continue;
dfs(u,v);
}
}
void dfs2(int v){
visited[v]=true;
for(auto u:adj2[v]){
if(visited[u]) continue;
dfs2(u);
}
ord.push_back(v);
}
void dfs3(int v,int cur){
visited[v]=true;
scc[v]=cur;
if(v<=k) sz[cur]++;
for(auto u:adjr[v]){
if(visited[u]) continue;
dfs3(u,cur);
}
}
int lca(int a,int b){
if(depth[a]<depth[b]) swap(a,b);
int len=depth[a]-depth[b];
for(int i=0;i<B;i++){
if(len&(1<<i)) a=up[a][i];
}
if(a==b) return a;
for(int i=B-1;i>=0;i--){
int ta=up[a][i];
int tb=up[b][i];
if(ta!=tb){
a=ta;
b=tb;
}
}
return up[a][0];
}
int main() {_
cin>>n>>k;
for(int i=0;i<n-1;i++){
int a,b;
cin>>a>>b;
adj[a].push_back(b);
adj[b].push_back(a);
}
for(int i=1;i<=n;i++){
cin>>c[i];
belong[c[i]].push_back(i);
}
dfs(1);
for(int j=1;j<B;j++){
for(int i=1;i<=n;i++){
up[i][j]=up[up[i][j-1]][j-1];
}
}
for(int i=1;i<=k;i++){
L[i]=belong[i][0];
for(int j=1;j<(int)belong[i].size();j++){
L[i]=lca(L[i],belong[i][j]);
}
}
int cnt=k;
for(int i=1;i<=n;i++){
id[i][0]=c[i];
}
for(int j=1;j<B;j++){
for(int i=1;i<=n;i++){
id[i][j]=++cnt;
adj2[id[i][j]].push_back(id[i][j-1]);
adj2[id[i][j]].push_back(id[up[i][j-1]][j-1]);
}
}
for(int i=1;i<=k;i++){
//cout<<L[i]<<'\n';
for(auto v:belong[i]){
int bit=__lg(depth[v]-depth[L[i]]+1);
adj2[i].push_back(id[v][bit]);
int len=depth[v]-(depth[L[i]]+(1<<bit)-1);
int x=v;
for(int j=0;j<B;j++){
if(len&(1<<j)) x=up[x][j];
}
adj2[i].push_back(id[x][bit]);
//cout<<v<<' '<<x<<' '<<bit<<'\n';
}
}
for(int i=1;i<=cnt;i++){
for(auto u:adj2[i]){
adjr[u].push_back(i);
}
}
fill(visited+1,visited+cnt+1,false);
for(int i=1;i<=cnt;i++){
if(!visited[i]){
dfs2(i);
}
}
reverse(all(ord));
fill(visited+1,visited+cnt+1,false);
int sccnt=0;
for(auto i:ord){
if(!visited[i]){
++sccnt;
dfs3(i,sccnt);
}
}
for(int i=1;i<=cnt;i++){
for(auto u:adj2[i]){
if(scc[u]!=scc[i]) out[scc[i]]++;
}
}
int ans=inf;
for(int i=1;i<=sccnt;i++){
if(out[i]==0 and sz[i]>0) ans=min(ans,sz[i]-1);
}
cout<<ans<<'\n';
return 0;
}
//maybe its multiset not set
//yeeorz
//laborz
Compilation message (stderr)
capital_city.cpp: In function 'void setIO(std::string)':
capital_city.cpp:15:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
15 | freopen((s + ".in").c_str(), "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
capital_city.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
16 | freopen((s + ".out").c_str(), "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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