Submission #1072433

#	Time	Username	Problem	Language	Result	Execution time	Memory
1072433		PagodePaiva	Race (IOI11_race)	C++17	100 / 100	317 ms	89012 KiB

race

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

using namespace std;

const int N = 200010;
map <int, int> m[N];
int shift[N];
int k;
vector <pair <int, int>> g[N];
int res[N];
int h[N];

void prep(int v, int p){
  for(auto [x, _] : g[v]){
    if(x == p) continue;
    h[x] = h[v]+1;
    prep(x, v);
  }
  return;
}

void dfs(int v, int p){
  m[v][0] = h[v];
  for(auto [x, w] : g[v]){
    if(x == p) continue;
    dfs(x, v);
    shift[x] += w;
    if(m[x].size() > m[v].size()){
      swap(m[x], m[v]);
      swap(shift[x], shift[v]);
    }
    for(auto [vvalor, altura] : m[x]){
      int valor = vvalor;
      valor = valor+shift[x];
      valor = k-valor;
      valor = valor-shift[v];
      if(m[v].find(valor) != m[v].end()){
        int altura2 = m[v][valor];
        // cout << altura << ' ' << altura2 << ' ' << v << '\n';
        res[v] = min(res[v], altura+altura2-2*h[v]);
      }
    }
    for(auto [vvalor, altura] : m[x]){
      int valor = vvalor;
      valor = valor+shift[x]-shift[v];
      if(m[v].find(valor) != m[v].end()) m[v][valor] = min(m[v][valor], altura);
      else m[v][valor] = altura;
    }
  }
  return;
}

int best_path(int n, int K, int h[][2], int l[]){
  k = K;
  for(int i = 0;i < n-1;i++){
    int a = h[i][0], b = h[i][1];
    g[a].push_back({b, l[i]});
    g[b].push_back({a, l[i]});
  }
  for(int i = 0;i < n;i++) res[i] = 1e8;
  prep(0,0);
  dfs(0,0);
  int resposta = 1e8;
  for(int i= 0;i < n;i++) {
    //cout << res[i] << ' ';
    resposta = min(resposta, res[i]);
  }
  return (resposta == 1e8 ? -1 : resposta);
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 22 / 22
• Subtask 4: 57 / 57