Submission #1131481

#	Time	Username	Problem	Language	Result	Execution time	Memory
1131481		duckindog	Sequence (APIO23_sequence)	C++17	100 / 100	885 ms	56620 KiB

sequence

#include <bits/stdc++.h>

using namespace std;

#ifndef LOCAL
#include "sequence.h"
#endif

const int N = 500'000 + 10;
int n;
int a[N];
vector<int> pos[N];

namespace IT { 
  struct Node { 
    int mi, ma;
    Node() : mi(1'000'000), ma(-1'000'000) {}
    Node(int mi, int ma) : mi(mi), ma(ma) {} 
    friend ostream& operator << (ostream& os, Node rhs) { 
      return os << rhs.mi << " " << rhs.ma;
    }
  } f[N << 2];
  int lazy[N << 2];
  
  inline Node merge(const Node& lt, const Node& rt) { 
    return Node(min(lt.mi, rt.mi), max(lt.ma, rt.ma));
  }

  void build(int s, int l, int r) { 
    f[s] = Node(0, 0);
    lazy[s] = 0;
    if (l == r) return;
    int mid = (l + r) >> 1;
    build(s << 1, l, mid); build(s << 1 | 1, mid + 1, r);
  }

  void push(int s) { 
    if (!lazy[s]) return;
    f[s << 1].mi += lazy[s];  f[s << 1 | 1].mi += lazy[s];
    f[s << 1].ma += lazy[s];  f[s << 1 | 1].ma += lazy[s];
    lazy[s << 1] += lazy[s];  lazy[s << 1 | 1] += lazy[s];
    lazy[s] = 0;
  }
  void update(int s, int l, int r, int u, int v, int x) { 
    if (v < l || u > r) return;
    if (u <= l && r <= v) { 
      f[s].mi += x;
      f[s].ma += x;
      lazy[s] += x;
      return;
    }
    push(s);
    int mid = (l + r) >> 1;
    update(s << 1, l, mid, u, v, x); update(s << 1 | 1, mid + 1, r, u, v, x);
    f[s] = merge(f[s << 1], f[s << 1 | 1]);
  }
  Node query(int s, int l, int r, int u, int v) { 
    if (v < l || u > r) return Node();
    if (u <= l && r <= v) return f[s];
    push(s);
    int mid = (l + r) >> 1;
    return merge(query(s << 1, l, mid, u, v), query(s << 1 | 1, mid + 1, r, u, v));
  }
}

int sequence(int inN, std::vector<int> inA) {
  { // input
    n = inN;
    for (int i = 1; i <= n; ++i) a[i] = inA[i - 1];
  }
  for (int i = 1; i <= n; ++i) pos[i] = {0};
  for (int i = 1; i <= n; ++i) pos[a[i]].push_back(i);

  int answer = 1;
  IT::build(1, 1, n);
  for (int i = 1; i <= n; ++i) 
    IT::update(1, 1, n, i, n, 1);

  for (int index = 1; index <= n; ++index) { 
    for (int i = 1; i < (int)pos[index].size(); ++i) 
      IT::update(1, 1, n, pos[index][i], n, -2);
    
    for (int i = pos[index].size() - 1; i >= 1; --i) { 
      int p = pos[index][i];
      IT::update(1, 1, n, p, n, 2);

      auto valueL = IT::merge({0, 0}, IT::query(1, 1, n, 1, p - 1));
      while (i + answer < (int)pos[index].size()) { 
        int r = pos[index][i + answer];
        auto valueR = IT::query(1, 1, n, r, n);
        valueR.mi -= 2 * (answer + 1);

        if (max(valueL.mi, valueR.mi) > min(valueL.ma, valueR.ma)) break;
        answer += 1;
      }
    }

    for (int i = 1; i < (int)pos[index].size(); ++i) 
      IT::update(1, 1, n, pos[index][i], n, -2);
  }

  return answer;
}

#ifdef LOCAL
int main() {
  int N;
  assert(1 == scanf("%d", &N));

  std::vector<int> A(N);
  for (int i = 0; i < N; ++i) {
    assert(1 == scanf("%d", &A[i]));
  }

  int result = sequence(N, A);
  printf("%d\n", result);
  return 0;
}
#endif

• Subtask 1: 11 / 11
• Subtask 2: 17 / 17
• Subtask 3: 7 / 7
• Subtask 4: 12 / 12
• Subtask 5: 13 / 13
• Subtask 6: 22 / 22
• Subtask 7: 18 / 18