Submission #346177

#	Time	Username	Problem	Language	Result	Execution time	Memory
346177		casperwang	Dancing Elephants (IOI11_elephants)	C++14	26 / 100	2050 ms	2952 KiB

elephants

#include "elephants.h"
#include <bits/stdc++.h>
#define pb push_back
#define All(x) x.begin(), x.end()
#define pii pair<int,int>
#define ff first
#define ss second
using namespace std;
#define debug(args...) kout("[ " + string(#args) + " ]", args)
void kout() { cerr << endl; }
template <class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ',kout(b...); }
template <class T> void pary(T L, T R) { while (L != R) cerr << *L << " \n"[++L==R]; }

const int MAXN = 150000;
const int K = 380;
int n, m, seg;
vector <pii> a;
vector <vector<pii>> B;
vector <pii> rng;
vector <int> pos;
vector <pii> info;

void build_block(int id) {
  int len = B[id].size();
  sort(All(B[id]));
  for (int i = len-1; i >= 0; i--) {
    pos[B[id][i].ss] = id;
    auto it = upper_bound(All(B[id]), pii(B[id][i].ff + seg, n));
    if (it == B[id].end()) {
      info[B[id][i].ss] = pii(1, B[id][i].ff + seg);
    } else {
      info[B[id][i].ss] = pii(info[it->ss].ff + 1, info[it->ss].ss);
    }
  }
  rng[id] = pii(B[id][0].ff, B[id][len-1].ff);
}

void build() {
  sort(All(a));
  for (int i = 0; i < m; i++)
    B[i].clear();
  for (int i = 0; i < n; i++)
    B[i/K].pb(a[i]);
  for (int i = 0; i < m; i++)
    build_block(i);
}

void init(int N, int L, int X[]) {
  n = N, m = (n-1)/K+1, seg = L;
  a.clear(), a.resize(n);
  pos.clear(), pos.resize(n);
  info.clear(), info.resize(n);
  B.clear(), B.resize(m);
  rng.clear(), rng.resize(m);
  for (int i = 0; i < n; i++)
    a[i].ff = X[i], a[i].ss = i;
  build();
  sort(All(a), [](const pii x, const pii y) {
    return x.ss < y.ss;
  });
}

int solve() {
  int ans = 0, now = -1;
  for (int i = 0; i < m; i++) {
    pii tmp = *upper_bound(All(B[i]), pii(now, n+1));
    ans += info[tmp.ss].ff;
    now = info[tmp.ss].ss;
  }
  return ans;
}
 
int update(int i, int y) {
  int id = pos[i];
  vector <pii> tmp(B[id].size()-1);
  int c = 0;
  for (int j = 0; j < B[id].size(); j++) {
    if (B[id][j].ss == i) continue;
    tmp[c++] = B[id][j];
  }
  B[id] = tmp;
  build_block(id);
  assert(a[i].ss == i);
  a[i].ff = y;
  for (int j = 0; j < m; j++) {
    if ((!j || rng[j-1].ss <= a[i].ff) && (j==m-1 || rng[j+1].ff >= a[i].ff)) {
      B[j].pb(a[i]);
      build_block(j);
      break;
    }
  }
  return solve();
}

Compilation message (stderr)

elephants.cpp: In function 'int update(int, int)':
elephants.cpp:77:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   77 |   for (int j = 0; j < B[id].size(); j++) {
      |                   ~~^~~~~~~~~~~~~~

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