Submission #1277300

#	Time	Username	Problem	Language	Result	Execution time	Memory
1277300		julia_08	Village (BOI20_village)	C++20	100 / 100	79 ms	28116 KiB

Village

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

using ll = long long;

const int MAXN = 1e5 + 10;

int to[MAXN];

int sub[MAXN];

int p[MAXN];

int deg[MAXN], marc[MAXN];

vector<int> adj[MAXN], c[MAXN];

int n;

void dfs_1(int v, int p){

  sub[v] = 1;

  for(auto u : adj[v]){
    if(u != p){
      dfs_1(u, v);
      sub[v] += sub[u];
    }
  }

}

int get_centroid(int v, int p){

  for(auto u : adj[v]){
    if(u != p){
      if(sub[u] > n / 2) return get_centroid(u, v);
    }
  }

  return v;

}

void dfs_2(int v, int p, vector<int> &vtx){

  vtx.push_back(v);

  for(auto u : adj[v]){
    if(u != p){
      dfs_2(u, v, vtx);
    }
  }

}

int32_t main(){
  cin.tie(0)->sync_with_stdio(0);

  cin >> n;

  for(int i=1; i<n; i++){
    
    int a, b; cin >> a >> b;
    
    adj[a].push_back(b);
    adj[b].push_back(a);
    
    deg[a] ++; deg[b] ++;

  }
  
  // min: 
  
  queue<int> q;

  for(int i=1; i<=n; i++){
    if(deg[i] == 1){
      q.push(i);
    }
  }

  ll ans_min = 0;

  while(!q.empty()){

    int v = q.front();
    q.pop();

    if(!c[v].empty()){

      marc[v] = 1;

      int sz = (int) c[v].size();

      ans_min += 2 * sz;

      if(sz % 2 == 0){

        while(sz > 2){

          auto [a, b] = make_pair(c[v][sz - 2], c[v][sz - 1]);

          p[a] = b;
          p[b] = a;

          sz -= 2;

        }

        auto [a, b] = make_pair(c[v][0], c[v][1]);

        p[v] = a;
        p[b] = v;
        p[a] = b;

      } else{

        while(sz > 1){

          auto [a, b] = make_pair(c[v][sz - 2], c[v][sz - 1]);

          p[a] = b;
          p[b] = a;

          sz -= 2;

        }

        p[v] = c[v][0];
        p[c[v][0]] = v;

      }

    }

    for(auto u : adj[v]){

      deg[u] --;
      if(!marc[v]) c[u].push_back(v);

      if(deg[u] == 1) q.push(u);

    }

  }

  for(int i=1; i<=n; i++){
    if(p[i] == 0){

      p[i] = i;
      swap(p[i], p[adj[i][0]]);

      ans_min += 2;

    }
  }

  // max:
  
  dfs_1(1, 1);

  int c = get_centroid(1, 1);

  dfs_1(c, c);

  vector<pair<int, int>> to_add;

  for(auto u : adj[c]) to_add.push_back({sub[u], u});

  sort(to_add.rbegin(), to_add.rend());

  vector<int> vtx;

  for(auto [x, u] : to_add) dfs_2(u, c, vtx);

  vtx.push_back(c);

  int sz = (int) vtx.size();

  for(int i=0; i<sz; i++) vtx.push_back(vtx[i]);

  int k = to_add[0].first;

  for(int i=0; i<sz; i++) to[vtx[i]] = vtx[i + k];
  
  ll ans_max = 0;

  for(int i=1; i<=n; i++) ans_max += 2 * min(sub[i], n - sub[i]);

  cout << ans_min << " " << ans_max << "\n";

  for(int i=1; i<=n; i++) cout << p[i] << " ";

  cout << "\n";

  for(int i=1; i<=n; i++) cout << to[i] << " ";

  cout << "\n";

  return 0;
}

• Subtask 1: 12 / 12
• Subtask 2: 38 / 38
• Subtask 3: 50 / 50