Submission #1220867

#	Time	Username	Problem	Language	Result	Execution time	Memory
1220867		HappyCapybara	Dancing Elephants (IOI11_elephants)	C++20	26 / 100	8 ms	1348 KiB

elephants

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

int k = 400;
int n, l, t;
vector<int> pos, eb;

struct bucket {
  int es[805], rc[805], rp[805], s;

  bucket(){
    s = 0;
  };

  void create(vector<int> v){
    s = v.size();
    for (int i=0; i<s; i++) es[i] = v[i];
  }

  void add(int el){
    es[s] = el;
    int cur = s;
    s++;
    while (cur && pos[es[cur]] < pos[es[cur-1]]){
      swap(es[cur], es[cur-1]);
      cur--;
    }
  }

  void del(int el){
    bool found = false;
    for (int i=0; i<s; i++){
      if (found) es[i-1] = es[i];
      if (es[i] == el) found = true;
    }
    s--;
  }

  void calc(){
    int next = s;
    for (int i=s-1; i>=0; i--){
      while (next && pos[es[next-1]] > pos[es[i]]+l) next--;
      if (next == s){
        rc[i] = 1;
        rp[i] = pos[es[i]]+l;
      }
      else {
        rc[i] = 1+rc[next];
        rp[i] = rp[next];
      }
    }
  }
};

vector<bucket*> buckets;

void build(){
  vector<int> v(n);
  for (int i=0; i<n; i++) v[i] = i;
  sort(v.begin(), v.begin(), [](int a, int b){return pos[a] < pos[b];});
  int cb = 0;
  vector<int> cv;
  for (int i=0; i<n; i++){
    cv.push_back(v[i]);
    eb[v[i]] = cb;
    if (i % k == k-1 || i == n-1){
      buckets[cb]->create(cv);
      buckets[cb]->calc();
      cb++;
      cv.clear();
    }
  }
}

int solve(){
  int ans = 0;
  int cur = -1;
  for (int i=0; i<(int)buckets.size(); i++){
    bucket* cb = buckets[i];
    if (!cb->s) continue;
    int l = -1, r = cb->s;
    while (l < r-1){
      int mid = (l+r)/2;
      if (pos[cb->es[mid]] > cur) r = mid;
      else l = cur;
    }
    if (r == cb->s) continue;
    ans += cb->rc[r];
    cur = cb->rp[r];
  }
  return ans;
}

void init(int N, int L, int X[]){
  n = N;
  l = L;
  pos.resize(n);
  for (int i=0; i<N; i++) pos[i] = X[i];
  eb.resize(n);
  for (int i=0; i<=n/k; i++) buckets.push_back(new bucket());
  build();
  t = 0;
  return;
}

int update(int i, int y){
  t++;
  if (t == k){
    pos[i] = y;
    t = 0;
    build();
    return solve();
  }
  buckets[eb[i]]->del(i);
  buckets[eb[i]]->calc();
  pos[i] = y;
  int nb = 0;
  for (int pb = 1; pb < (int)buckets.size(); pb++){
    if (buckets[pb]->s && pos[buckets[pb]->es[0]] <= pos[i]) nb = pb;
  }
  buckets[nb]->add(i);
  eb[i] = nb;
  buckets[nb]->calc();
  return solve();
}

• Subtask 1: 10 / 10
• Subtask 2: 16 / 16
• Subtask 3: 0 / 24
• Subtask 4: 0 / 47
• Subtask 5: 0 / 3