Submission #789513

#	Time	Username	Problem	Language	Result	Execution time	Memory
789513		anton	Cats or Dogs (JOI18_catdog)	C++17	0 / 100	1 ms	596 KiB

catdog

#include "catdog.h"
#include<bits/stdc++.h>

using namespace std;
#define pii pair<int, int>

const int N_MAX = 1e5;
int n, t[N_MAX];
bool vis[N_MAX];
vector<vector<int>> adj;
vector<vector<int>> ch;


void dfs(int id){
  //cout<<"dfs "<<id<<endl;
  vis[id] = true;

  for(auto e: adj[id]){
    if(!vis[e]){
      ch[id].push_back(e);
      dfs(e);
    }
  }
}

void initialize(int N, std::vector<int> A, std::vector<int> B) {
  n = N;
  adj.resize(n);
  ch.resize(n);
  fill(t, t+N_MAX, -1);

  for(int i = 0; i<n-1; i++){
    int a = A[i]-1;
    int b=  B[i]-1;

    adj[a].push_back(b);
    adj[b].push_back(a);
  }

  dfs(0);
}

pii dp(int i){
  int s= 0, oc[2] = {0, 0};

  for(auto e: ch[i]){
    pii r = dp(e);
    s+=r.first;
    if(r.second!=-1){
      oc[r.second]++;
    }
  }

  pii res;
  if(t[i] == -1){
    res = pii(s +min(oc[0], oc[1]), -1);
    if(oc[0]<oc[1]){
      res.second = 1;
    }
    else if(oc[0]>oc[1]){
      res.second = 0;
    }
    else{
      res.second = -1;
    }
  }
  else{
    res= pii(s+ oc[t[i]^1], t[i]);
  }

  //cout<<"dp "<<i<<" "<<res.first<<" "<<res.second<<endl;
  return res;
}


int cat(int v) {
  t[v] = 0;
  return dp(0).first;
}

int dog(int v) {
  t[v]=1;
  return dp(0).first;
}

int neighbor(int v) {
  t[v] = -1;
  return dp(0).first;
}

• Subtask 1: 0 / 8
• Subtask 2: 0 / 30
• Subtask 3: 0 / 62