Submission #315350

#	Time	Username	Problem	Language	Result	Execution time	Memory
315350		VROOM_VARUN	Dancing Elephants (IOI11_elephants)	C++14	26 / 100	24 ms	1792 KiB

elephants

/*
ID: varunra2
LANG: C++
TASK: elephants
*/

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

#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
  cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif

#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second

const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions

int n, l;
const int BLOCK = 400;

multiset<PII> st;
VI vals;

struct block {
  VI pnts;
  int siz;

  VI dp1;  // how many blocks for suffix starting at i, ending at pnts.size()?
  VI dp2;  // where does the optimal solution held at dp1[i] end?

  void init() {
    sort(all(pnts));
    siz = sz(pnts);
    dp1.clear();
    dp2.clear();
    dp1.resize(siz);
    dp2.resize(siz);
  }

  void calc() {
    init();
    int p1 = siz - 1;
    for (int i = siz - 1; i >= 0; i--) {
      while ((pnts[p1] - pnts[i]) > l) p1--;
      if (p1 == siz - 1) {
        dp1[i] = 1;
        dp2[i] = pnts[i] + l + 1;
      } else {
        dp1[i] = dp1[p1 + 1] + 1;
        dp2[i] = dp2[p1 + 1];
      }
    }
  }

  void ins(int x) {
    pnts.PB(x);
    calc();
  }

  void del(int x) {
    VI cop;
    trav(xx, pnts) {
      if (xx == x) continue;
      cop.PB(xx);
    }
    pnts = cop;
    calc();
  }

  PII get(int x) {
    // how many to cover rest of this block starting at x
    // where would it end at
    auto it = lower_bound(all(pnts), x);
    if (it == pnts.end()) {
      return MP(0, x);
    }
    int ind = it - pnts.begin();
    return MP(dp1[ind], dp2[ind]);
  }
};

vector<block> blocks;

void rebuild(bool done = true) {
  // we are rebuilding blocks
  VI pnts;

  pnts = vals;

  blocks.clear();
  sort(all(pnts));
  VI cur;

  st.clear();

  for (int i = 0; i < sz(pnts); i++) {
    cur.PB(pnts[i]);
    st.insert(MP(pnts[i], sz(blocks)));
    if (sz(cur) == BLOCK) {
      block nw;
      nw.pnts = cur;
      nw.calc();
      cur.clear();
      blocks.PB(nw);
    }
  }
  if (!cur.empty()) {
    block nw;
    nw.pnts = cur;
    nw.calc();
    cur.clear();
    blocks.PB(nw);
  }
}

void ins(int x) {
  // what block are we in?
  auto xx = *st.lower_bound(MP(x, -1));
  blocks[xx.y].ins(x);
  st.insert(MP(x, xx.y));
}

void del(int x) {
  auto xx = *st.lower_bound(MP(x, -1));
  blocks[xx.y].del(x);
  st.erase(st.lower_bound(MP(x, -1)));
}

int qry() {
  int ret = 0;
  int ind = -1;
  for (int i = 0; i < sz(blocks); i++) {
    auto x = blocks[i].get(ind);
    ret += x.x;
    ind = x.y;
  }
  return ret;
}

void init(int N, int L, int X[]) {
  n = N;
  l = L;
  for (int i = 0; i < n; i++) {
    vals.PB(X[i]);
  }
  rebuild(false);  // first time building
}

int cnt = 0;

int update(int i, int y) {
  int cur = vals[i];
  vals[i] = y;
  del(cur);
  ins(y);
  cnt++;
  if (cnt % BLOCK == 0) {
    rebuild();
  }
  return qry();
}

// int main() {
// #ifndef ONLINE_JUDGE
//   freopen("elephants.in", "r", stdin);
//   freopen("elephants.out", "w", stdout);
// #endif
//   cin.sync_with_stdio(0);
//   cin.tie(0);

//   int n, l;
//   int x[n];

//   int q;

//   cin >> n >> l;

//   for (int i = 0; i < n; i++) {
//     cin >> x[i];
//   }

//   init(n, l, x);

//   cin >> q;

//   while (q--) {
//     int i, y;
//     cin >> i >> y;
//     cout << update(i, y) << '\n';
//   }

//   return 0;
// }

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