Submission #465418

#	Time	Username	Problem	Language	Result	Execution time	Memory
465418		MatheusLealV	Highway Tolls (IOI18_highway)	C++17	51 / 100	305 ms	19596 KiB

highway

#include "highway.h"
#define f first
#define ss second
#define pb push_back
#define mp make_pair
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
#define N 90005
vector<int> caras,especiais;
vector<pii> grafo[N], tree[N];
int pai[N], n, m, id_pai[N],A,B, dist_st;
void dfs(int x, int p){
	pai[x]=p;
	caras.pb(x);
	for(auto v: tree[x]){
		if(v.f == p) continue;
		id_pai[v.f] =v.ss;
		dfs(v.f, x);
	}
}

int get(int root){
  caras.clear();
  dfs(root,root);
  int ini = 1, fim = sz(caras)-1,mid,best=-1;
  while(fim >=ini){
    mid = (ini + fim)/2;
    vector<int> w(m);
    for(int i=0;i<m;i++)w[i]=1;
    for(int i = 0; i <sz(especiais); i++) w[especiais[i]]=0;
    for(int i = 1; i <= mid; i++) w[id_pai[caras[i]]] = 1;
    int dmid = ask(w);
    if(dmid == B*dist_st){
      best=mid;
      fim=mid-1;
    }else ini=mid+1;
  }
  return caras[best];
}
void find_pair(int N_, std::vector<int> U, std::vector<int> V, int AA, int BB) {
  n=N_;A=AA;B=BB;m=sz(U);
  for(int i = 0; i < sz(U); i++){
  	grafo[U[i]].pb({V[i],i}); grafo[V[i]].pb({U[i],i});
  }
  vector<int>w(m);
  dist_st = ask(w)/A;
  int ini = 0, fim = n-1,mid,root=-1;
  while(fim>=ini){
    mid=(ini+fim)/2;
    vector<int> w(m);
    for(int i = 0; i < m; i++) w[i]=0;
    for(int x = 0; x <= mid; x++){
      for(auto v: grafo[x]) w[v.ss] = 1;
    }
    if(ask(w) != A*dist_st){
      root = mid;
      break;
    }
    else ini=mid+1;
  }
  assert(root!=-1);
  vector<int>vis(n);
  queue<int>fila;
  fila.push(root); vis[root]=1;
  while(!fila.empty()){
    int x=fila.front();fila.pop();
    for(auto v: grafo[x]){
      if(!vis[v.f]){
        vis[v.f]=1;
        fila.push(v.f);
        tree[x].pb(v);
        tree[v.f].pb({x,v.ss});
        especiais.pb(v.ss);
      }
    }
  }

  int S = get(root);
  int T = get(S);
  answer(S, T);
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 6 / 6
• Subtask 4: 33 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31