Submission #626875

#	Time	Username	Problem	Language	Result	Execution time	Memory
626875		dnialh	Radio Towers (IOI22_towers)	C++17	0 / 100	143 ms	3496 KiB

towers

#include <vector>
#include <map>
#include <set>
#include <iostream>
#include <cassert>

#define map std::map
#define set std::set

#define vector std::vector
#define vi vector<int>

#define ll long long
#define pb push_back
#define vll vector<ll>


ll fd = -10;
ll n;

vi heights;
vector<vll> steppers;

void init(int N, vector<int> H){
  n = N;
  heights = H;
}

void compute(ll d){
  vi nhi(n + 1, n);

  ll best = -1;
  ll vb = -1;
  ll last = n;

  for (ll i = n - 1; i >= 0; i--){
    ll v = heights[i];

    if (v > vb){
      best = i;
      vb = v;
    }

    if (vb >= v + d){
      last = best;
      best = -1;
      vb = -1;

      //std::cout << "UPD HI " << i << " " << last << std::endl;

      for (ll j = i + 1; j < last; j++){
        if (heights[j] >= heights[i] + d){
          last = j;
          break;
        } 
      }

      best = i;
      vb = v;

      //std::cout << "UPD HI " << i << " " << last << std::endl;
    }

    nhi[i] = last;

    for (int j = i + 1; j < last; j++){
      if (heights[j] >= heights[i] + d){
        assert (false);
        //std::cout << "HI " << i << " " << j << " " << last << '\n'; 
      }
    }

    //std::cout << "nhi " << i << " " << last << std::endl; 
  }

  vi nlo(n + 1, n);

  ll lbest = -1;
  ll lvb = -2e9;
  ll llast = n;

  for (ll i = n - 1; i >= 0; i--){
    ll v = 0 - heights[i];

    if (v > lvb){
      lbest = i;
      lvb = v;
    }

    if (lvb >= v + d){
      llast = lbest;
      lbest = -1;
      lvb = -2e9;

      for (ll j = i + 1; j < llast; j++){
        if (heights[i] >= heights[j] + d){
          llast = j;
          break;
        } 
      }

      best = i;
      vb = v;
    }

    for (int j = i + 1; j < last; j++){
      if (heights[i] >= heights[j] + d){
        assert (false);
        //std::cout << "LO" << " " << i << " " << j << " " << llast << '\n'; 
      }
    }

    nlo[i] = llast;
  }

  steppers = vector<vll>();

  vll first;
  for (ll i = 0; i <= n; i++){
    first.pb(nlo[nhi[i]]);
  }

  steppers.pb(first);

  for (ll j = 0; j < 30; j++){
    vll nex;
    vll curr = steppers[j];

    for (ll i = 0; i <= n; i++){
      nex.pb(curr[curr[i]]);
    }

    steppers.pb(nex);
  }

  //std::cout << steppers.size() << std::endl;
}

int max_towers(int L, int R, int D){
  if (D != fd){
    compute(D);
    fd = D;
  }

  ll out = 1;
  ll curr = L;

  for (ll j = 29; j >= 0; j--){
    //std::cout << j << " " << out << " " << curr << std::endl;
    ll att = steppers[j][curr];
    if (att <= R){
      out += (1 << j);
      curr = att;
    }
  }

  return out;
}

/*
7 3
10 21 60 40 50 30 70
1 5 10
2 2 100
0 6 17
*/

• Subtask 1: 0 / 4
• Subtask 2: 0 / 11
• Subtask 3: 0 / 12
• Subtask 4: 0 / 14
• Subtask 5: 0 / 17
• Subtask 6: 0 / 19
• Subtask 7: 0 / 23