結果

問題 No.3075 Mex Recurrence Formula
ユーザー Nzt3
提出日時 2025-03-28 22:41:10
言語 C++23
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 707 ms / 2,000 ms
コード長 3,721 bytes
コンパイル時間 3,862 ms
コンパイル使用メモリ 292,980 KB
実行使用メモリ 28,332 KB
最終ジャッジ日時 2025-03-28 22:41:38
合計ジャッジ時間 17,000 ms
ジャッジサーバーID
(参考情報)
judge3 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 46
権限があれば一括ダウンロードができます

ソースコード

diff #

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

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
#define rep3(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define ov4(a, b, c, d, name, ...) name
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define per(i, a, b) for (ll i = (a) - 1; i >= (b); i--)
#define fore(e, v) for (auto&& e : v)
#define all(a) begin(a), end(a)
#define sz(a) (int)(size(a))
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define eb emplace_back

template <typename T, typename S>
bool chmin(T& a, const S& b) {
  return a > b ? a = b, 1 : 0;
}
template <typename T, typename S>
bool chmax(T& a, const S& b) {
  return a < b ? a = b, 1 : 0;
}
const int INF = 1e9 + 100;
const ll INFL = 3e18 + 100;
#define i128 __int128_t
struct _ {
  _() { cin.tie(0)->sync_with_stdio(0), cout.tie(0); }
} __;

namespace Lib {
  struct range_set {
    using all2 = array<long long, 2>;
    static constexpr ll minf = numeric_limits<ll>::min();
    static constexpr ll pinf = numeric_limits<ll>::max();
    set<all2> intervals;
    int add(all2 a) {
      auto [l, r] = a;
      int ret = 1;
      {
        auto it = intervals.upper_bound(all2({l, pinf}));
        if (it != intervals.begin()) {
          it--;
          if ((*it)[1] >= r) return 0;
          if ((*it)[1] >= l) l = (*it)[0];
        }
      }
      auto it = intervals.lower_bound(all2({l, minf}));
      while (1) {
        if (it != intervals.end() && (*it)[0] <= r) {
          r = max(r, (*it)[1]);
          auto it2 = it;
          it++;
          intervals.erase(it2);
          ret -= 1;
        } else {
          break;
        }
      }
      intervals.insert({l, r});
      return ret;
    }
    int erase(all2 a) {
      auto [l, r] = a;
      int ret = 0;
      {
        auto it = intervals.lower_bound(all2({l, minf}));
        if (it != intervals.begin()) {
          it--;
          if ((*it)[1] > l) {
            auto [l2, r2] = *it;
            intervals.erase(it);
            intervals.insert({l2, l});
            if (r2 > r) {
              intervals.insert({r, r2});
              ret += 1;
            }
          }
        }
      }
      auto it = intervals.lower_bound(all2({l, minf}));
      while (1) {
        if (it != intervals.end() && (*it)[1] <= r) {
          auto it2 = it;
          it++;
          intervals.erase(it2);
          ret -= 1;
        } else {
          break;
        }
      }
      if (it != intervals.end() && (*it)[0] < r) {
        auto [l2, r2] = *it;
        intervals.erase(it);
        intervals.insert({r, r2});
      }
      return ret;
    }
    pair<bool, all2> cover(all2 b) {
      auto [l, r] = b;
      auto it = intervals.upper_bound(all2({l, pinf}));
      if (it != intervals.begin()) {
        it--;
        if ((*it)[0] <= l && r <= (*it)[1]) {
          all2 ret = *it;
          return make_pair(true, ret);
        }
      }
      return make_pair(false, all2({0, 0}));
    }
  };
}

int main(){
  int N;
  ll X;
  cin>>N>>X;
  --X;
  vi A(N);
  fore(i,A)cin>>i;
  if(X<N){
    cout<<A[X]<<'\n';
    return 0;
  }
  Lib::range_set S;
  X-=N;
  using al2=array<ll,2>;
  map<int,int>cnt;
  fore(i,A){
    cnt[i]++;
    S.add(al2{i,i+1});
  }
  rep(i,N+1){
    auto [ex,a]=S.cover(al2{0,1});
    if(!ex){
      A.eb(0);   
      S.add(al2{0,1});
      cnt[0]++;
    }else{
      A.eb(a[1]);
      S.add(al2{a[1],a[1]+1});
      cnt[a[1]]++;
    }
    cnt[A[i]]--;
    if(cnt[A[i]]==0){
      S.erase(al2{A[i],A[i]+1});
    }
  }
  cout<<A[X%(N+1)+N]<<'\n';
}
0