Submission #480876

#	Time	Username	Problem	Language	Result	Execution time	Memory
480876		MilosMilutinovic	Index (COCI21_index)	C++14	110 / 110	1910 ms	59556 KiB

index

/**
 *    author: m371
 *    created: 18.10.2021 15:55:58
**/
#include <bits/stdc++.h>

using namespace std;

const int N = 2e5 + 5;
const int M = 20 * N;  

int st[M], ls[M], rs[M], tsz, root[N];

void modify(int prv, int& node, int l, int r, int x, int y) {
  node = ++tsz; ls[node] = ls[prv]; rs[node] = rs[prv]; st[node] = st[prv] + y;
  if (l == r) {
    return;
  }
  int mid = l + r >> 1;
  if (x <= mid) {
    modify(ls[prv], ls[node], l, mid, x, y);
  } else {
    modify(rs[prv], rs[node], mid + 1, r, x, y);
  }
}

int get(int node, int l, int r, int ll, int rr) {
  if (l > r || l > rr || r < ll) {
    return 0;
  }
  if (ll <= l && r <= rr) {
    return st[node];
  }              
  int mid = l + r >> 1;
  return get(ls[node], l, mid, ll, rr) + get(rs[node], mid + 1, r, ll, rr); 
} 

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, qq;
  cin >> n >> qq;
  vector<int> p(n);
  for (int i = 0; i < n; i++) {
    cin >> p[i];
  }
  vector<vector<int>> at(N);
  for (int i = 0; i < n; i++) {
    at[p[i]].push_back(i);
  }
  for (int i = N - 1; i >= 1; i--) {
    root[i] = root[i + 1];
    for (int j : at[i]) {
      modify(root[i], root[i], 0, n - 1, j, 1);
    }
  }
  while (qq--) {
    int l, r;
    cin >> l >> r;
    --l; --r;
    int low = 1, high = N - 1, ans = 0;
    while (low <= high) {
      int mid = low + high >> 1;
      if (get(root[mid], 0, n - 1, l, r) >= mid) {
        ans = mid;
        low = mid + 1;  
      } else {
        high = mid - 1;
      }
    }
    cout << ans << '\n';
  }
  return 0;
}

Compilation message (stderr)

index.cpp: In function 'void modify(int, int&, int, int, int, int)':
index.cpp:19:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   19 |   int mid = l + r >> 1;
      |             ~~^~~
index.cpp: In function 'int get(int, int, int, int, int)':
index.cpp:34:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   34 |   int mid = l + r >> 1;
      |             ~~^~~
index.cpp: In function 'int main()':
index.cpp:63:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   63 |       int mid = low + high >> 1;
      |                 ~~~~^~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 40 / 40
• Subtask 3: 50 / 50