Submission #981036

#	Time	Username	Problem	Language	Result	Execution time	Memory
981036		nnin	Sequence (APIO23_sequence)	C++17	0 / 100	2058 ms	385820 KiB

sequence

#include "sequence.h"
#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>

vector<int> ct[500005];
int N;
vector<pii> v;

struct node {
  int val;
  node *left, *right;
  node(int v) {
    val = v;
    left = right = NULL;
  }
};

struct persistTree {
  node *root;
  void build(node *cur, int l, int r) {
    if(l==r) return;
    int m = (l+r)/2;
    cur->left = new node(0);
    cur->right = new node(0);
    build(cur->left, l, m);
    build(cur->right, m+1, r);
  }
  void build() {
    root = new node(0);
    build(root, 0, N-1);
  }

  void update(node *cur, node *prev, int l, int r, int x) {
    if(l==r) {
      cur->val++;
      return;
    }
    int m = (l+r)/2;
    if(x<=m) {
      cur->left = new node(0);
      cur->right = prev->right;
      update(cur->left, prev->left, l, m, x);
    } else {
      cur->left = prev->left;
      cur->right = new node(0);
      update(cur->right, prev->right, m+1, r, x);
    }
    cur->val = cur->left->val+cur->right->val;
  }
  void update(node *prev, int x) {
    root = new node(0);
    update(root, prev, 0, N-1, x);
  }

  int query(node *add, node *sub, int l, int r, int wl, int wr) {
    if(wl>r || wr<l) return 0;
    if(wl<=l && wr>=r) return add->val-sub->val;
    int m = (l+r)/2;
    return query(add->left, sub->left, l, m, wl, wr) + query(add->right, sub->right, m+1, r, wl, wr);
  }
  int query(node *sub, int wl, int wr) {
    if(wr<wl) return 0;
    return query(root, sub, 0, N-1, wl, wr);
  }
};
vector<persistTree> persist;

bool check(int x) {
  for(int i=1;i<=N;i++) {
    for(int j=0;j+x-1<ct[i].size();j++) {
      int st = ct[i][j];
      int en = ct[i][j+x-1];
      int q1 = persist[lower_bound(v.begin(), v.end(), make_pair(i, -1))-v.begin()].query(persist[0].root, st+1, en-1);
      int q2 = persist[N].query(persist[upper_bound(v.begin(), v.end(), make_pair(i, (int)1e9))-v.begin()].root, st+1, en-1);
      if(abs(q1-q2)<=x) return true;
    }
  }
  return false;
}

int sequence(int n, std::vector<int> A) {
  N = n;
  for(int i=0;i<N;i++) {
    ct[A[i]].push_back(i);
    v.push_back({A[i], i});
  }
  sort(v.begin(), v.end());
  persist.resize(N+1);
  persist[0].build();
  for(int i=0;i<N;i++) {
    persist[i+1].update(persist[i].root, v[i].second);
  }
  int l = 1, r = 1;
  for(int i=1;i<=N;i++) {
    r = max(r, (int)ct[i].size());
  }
  while(l<r) {
    int m = (l+r+1)/2;
    if(check(m)) l = m;
    else r = m-1;
  }
  return l;
}

Compilation message (stderr)

sequence.cpp: In function 'bool check(int)':
sequence.cpp:71:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |     for(int j=0;j+x-1<ct[i].size();j++) {
      |                 ~~~~~^~~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 17
• Subtask 3: 0 / 7
• Subtask 4: 0 / 12
• Subtask 5: 0 / 13
• Subtask 6: 0 / 22
• Subtask 7: 0 / 18