제출 #877208

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
877208		NeroZein	서열 (APIO23_sequence)	C++17	100 / 100	1386 ms	64412 KiB

sequence

#include "sequence.h"
#include "bits/stdc++.h"

using namespace std; 

const int N = 5e5 + 5; 

struct node {
  int sum = 0;
  int suf_max = 0, pref_max = 0;
  int suf_min = 0, pref_min = 0; 
};

node comb(node lx, node rx) {
  node ret;
  ret.sum = lx.sum + rx.sum;
  ret.suf_max = max(rx.suf_max, rx.sum + lx.suf_max); 
  ret.pref_max = max(lx.pref_max, lx.sum + rx.pref_max);
  ret.suf_min = min(rx.suf_min, rx.sum + lx.suf_min);
  ret.pref_min = min(lx.pref_min, lx.sum + rx.pref_min); 
  return ret;
}

node init(int v) {
  node ret;
  ret.sum = v; 
  if (v == 1) {
    ret.suf_max = ret.pref_max = 1; 
  } else if (v == -1) {
    ret.suf_min = ret.pref_min = -1; 
  }
  return ret;
}

int sum[N]; 
int suf_max[N], pref_max[N]; 
int suf_min[N], pref_min[N];
node seg[N * 2]; 

void upd(int nd, int l, int r, int p, int v) {
  if (l == r) {
    seg[nd] = init(v); 
    return;
  }
  int mid = (l + r) >> 1;
  int rs = nd + ((mid - l + 1) << 1);
  if (p <= mid) {
    upd(nd + 1, l, mid, p, v); 
  } else {
    upd(rs, mid + 1, r, p, v); 
  }
  seg[nd] = comb(seg[nd + 1], seg[rs]); 
}

node qry(int nd, int l, int r, int s, int e) {
  if (l >= s && r <= e) {
    return seg[nd];
  }
  int mid = (l + r) >> 1;
  int rs = nd + ((mid - l + 1) << 1);
  if (mid >= e) {
    return qry(nd + 1, l, mid, s, e); 
  } else {
    if (mid < s) {
      return qry(rs, mid + 1, r, s, e); 
    } else {
      return comb(qry(nd + 1, l, mid, s, e), qry(rs, mid + 1, r, s, e)); 
    }
  }
}

void precalc(int n, vector<vector<int>>& group) {
  for (int x = 0; x < n; ++x) {
    for (int i : group[x]) {
      if (i > 0) {
        suf_min[i] = qry(0, 0, n - 1, 0, i - 1).suf_min;
      }
      if (i < n - 1) {
        pref_min[i] = qry(0, 0, n - 1, i + 1, n - 1).pref_min; 
      }
    }
    for (int i : group[x]) {
      upd(0, 0, n - 1, i, 0); 
    }
    for (int i : group[x]) {
      sum[i] = qry(0, 0, n - 1, 0, i).sum; 
    }
    for (int i : group[x]) {
      upd(0, 0, n - 1, i, 1); 
    }
    for (int i : group[x]) {
      if (i > 0) {
        suf_max[i] = qry(0, 0, n - 1, 0, i - 1).suf_max;
      }
      if (i < n - 1) {
        pref_max[i] = qry(0, 0, n - 1, i + 1, n - 1).pref_max;
      }
    }
  }
}

int sequence(int n, vector<int> a) {
  vector<vector<int>> group(n); 
  for (int i = 0; i < n; ++i) {
    --a[i]; 
    group[a[i]].push_back(i); 
  }
  for (int i = 0; i < n; ++i) {
    upd(0, 0, n - 1, i, -1); 
  }
  precalc(n, group); 
  int ans = 0; 
  for (int x = 0; x < n; ++x) {
    for (int i = 0; i < (int) group[x].size(); ++i) {
      int l = 0, r = i;
      while (l < r) {
        bool ok = true; 
        int mid = (l + r) / 2;
        int tsum = sum[group[x][i]] - sum[group[x][mid]]; 
        int cc = i - mid + 1; 
        if (tsum < 0) {
          cc += pref_max[group[x][i]];
          cc += suf_max[group[x][mid]]; 
          ok &= (tsum + cc >= 0); 
        } else if (tsum > 0) {
          cc -= pref_min[group[x][i]];
          cc -= suf_min[group[x][mid]]; 
          ok &= (tsum - cc <= 0); 
        }
        (ok ? r = mid : l = mid + 1); 
      }
      ans = max(ans, i - l + 1); 
    }
    for (int i : group[x]) {
      upd(0, 0, n - 1, i, 1); 
    }
  }
  return ans; 
}

• 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