Submission #1205175

#	Time	Username	Problem	Language	Result	Execution time	Memory
1205175		mychecksedad	Capital City (JOI20_capital_city)	C++20	100 / 100	386 ms	76536 KiB

capital_city

/* Author : Mychecksdead  */
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define pb push_back
#define all(x) x.begin(), x.end()
#define en cout << '\n'
#define ff first
#define ss second
#define pii pair<int,int>
#define vi vector<int>
const int N = 1e6+100, M = 1e5+10, K = 52, MX = 30;


int n, col[N], D = 0, k, s[N], ans, col_cnt[N], id[N], par[N], in_queue[N];
vi g[N], C[N];
bitset<N> vis = 0, used = 0;

void pre(int v, int p){
  id[v] = D;
  s[v] = 1;
  col_cnt[col[v]] = 0;
  in_queue[col[v]] = -1;
  for(int u: g[v]){
    if(u != p && !vis[u]){
      pre(u, v);
      s[v] += s[u];
    }
  }
}
void dfs(int v, int p){
  col_cnt[col[v]]++;
  used[v] = 0;
  for(int u: g[v]){
    if(u != p && !vis[u]){
      par[u] = v;
      dfs(u, v);
    }
  }
}
int num;
int centro(int v, int p){
  for(int u: g[v]){
    if(u == p || vis[u]) continue;
    if(s[u] >= (num+1)/2) return centro(u, v);
  }
  return v;
}

void f(int v){
  ++D;
  pre(v, v);
  num = s[v];
  v = centro(v, v);
  dfs(v, v);

  bool ok = true;

  queue<int> q;
  q.push(col[v]);
  in_queue[col[v]] = 1;
  int res = 0;
  used[v] = 1;
  while(!q.empty() && ok){
    ++res;
    int c = q.front(); q.pop();
    for(int u: C[c]){
      if(id[u] != D){
        ok = false;
        break;
      }
      while(u != v && !used[u]){
        used[u] = 1;
        if(in_queue[col[u]] == -1){
          q.push(col[u]);
          in_queue[col[u]] = 1;
        }
        u = par[u];
      }
    }
  }


  if(ok){
    ans = min(ans, res);
  }
  vis[v] = 1;
  for(int u: g[v]){
    if(!vis[u]) f(u);
  }
}

void solve(){
  cin >> n >> k;
  for(int i = 1; i < n; ++i){
    int u, v; cin >> u >> v;
    g[u].pb(v); 
    g[v].pb(u); 
  }
  for(int i = 1; i <= n; ++i){
    int c; cin >> c;
    C[c].pb(i);
    col[i] = c;
  }
  ans = k;
  f(1);
  cout << ans - 1;
}


int main(){
  cin.tie(0); ios::sync_with_stdio(0);
  int tt = 1, aa;
  // freopen("in.txt", "r", stdin);
  // freopen("out.txt", "w", stdout);
  while(tt--){
    solve();
    en;
  }
  cerr<<"time taken : "<<(float)clock()/CLOCKS_PER_SEC<<" seconds\n";
  return 0;
} 

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