Submission #682629

#TimeUsernameProblemLanguageResultExecution timeMemory
682629Alex_tz307Index (COCI21_index)C++17
110 / 110
2396 ms132852 KiB
#include <bits/stdc++.h>
 
using namespace std;
 
const int N = 2e5;
 
struct node {
  node *l;
  node *r;
  int sum;
 
  node() : sum(0) {
    l = nullptr;
    r = nullptr;
  }
} *roots[1 + N];
 
void build(node *root, int lx, int rx) {
  if (lx == rx) {
    return;
  }
 
  int mid = (lx + rx) / 2;
 
  root->l = new node;
  build(root->l, lx, mid);
 
  root->r = new node;
  build(root->r, mid + 1, rx);
}
 
void update(node *prevRoot, node *root, int lx, int rx, int pos, int val) {
  if (lx == rx) {
    root->sum = prevRoot->sum + val;
    return;
  }
 
  int mid = (lx + rx) / 2;
 
  if (pos <= mid) {
    root->l = new node;
 
    root->r = prevRoot->r;
 
    update(prevRoot->l, root->l, lx, mid, pos, val);
  } else {
    root->l = prevRoot->l;
 
    root->r = new node;
 
    update(prevRoot->r, root->r, mid + 1, rx, pos, val);
  }
 
  root->sum = root->l->sum + root->r->sum;
}
 
int query(node *root, int lx, int rx, int st, int dr) {
  if (st <= lx && rx <= dr) {
    return root->sum;
  }
 
  int mid = (lx + rx) / 2;
 
  int sum = 0;
 
  if (st <= mid) {
    sum += query(root->l, lx, mid, st, dr);
  }
 
  if (mid < dr) {
    sum += query(root->r, mid + 1, rx, st, dr);
  }
 
  return sum;
}
 
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
 
  int n, q;
  cin >> n >> q;
 
  roots[0] = new node;
  build(roots[0], 1, N);
 
  for (int i = 1; i <= n; ++i) {
    int x;
    cin >> x;
 
    roots[i] = new node;
    update(roots[i - 1], roots[i], 1, N, x, 1);
  }
 
  for (int i = 0; i < q; ++i) {
    int l, r;
    cin >> l >> r;
 
    int st = 2, dr = r - l + 1, res = 1;
 
    while (st <= dr) {
      int mid = (st + dr) / 2;
 
      if (query(roots[r], 1, N, mid, N) - query(roots[l - 1], 1, N, mid, N) >= mid) {
        res = mid;
        st = mid + 1;
      } else {
        dr = mid - 1;
      }
    }
 
    cout << res << '\n';
  }
 
  return 0;
}
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