// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#ifdef _DEBUG
int find_best(int n);
std::vector<int> ask(int i);
#else
#include "prize.h"
#endif
vector<int> a;
vector<int> b;
int N;
int segSet(int l, int r, int i, int k, int x)
{
if (l > k || r <= k)
return b[i];
if (l + 1 == r)
return a[l] = b[i] = x;
int m = (l + r) / 2;
return b[i] = segSet(l, m, i * 2 + 1, k, x) + segSet(m, r, i * 2 + 2, k, x);
}
int segGet(int l, int r, int i, int ql, int qr)
{
if (ql <= l && qr >= r)
return b[i];
if (ql >= r || qr <= l)
return 0;
int m = (l + r) / 2;
return segGet(l, m, i * 2 + 1, ql, qr) + segGet(m, r, i * 2 + 2, ql, qr);
}
int asks = 0;
int getRecursive(int l, int r, int cnt_here, int cnt_l, int cnt_r)
{
if (l >= r)
return -1;
if (cnt_here <= 0)
return -1;
int m = (l + r) / 2;
int i = m;
vector<int> answer;
bool is_special = false;
int diff_l = 0;
int diff_r = 0;
do
{
if (i == r)
break;
is_special = false;
asks++;
assert(asks < 10000);
assert(i >= 0 && i < n);
answer = ask(i);
if (answer[0] + answer[1] == 0)
return i;
answer[0] -= cnt_l;
answer[1] -= cnt_r;
if (answer[0] + answer[1] != cnt_here)
{
is_special = true;
i++;
}
else
{
answer[0] -= i - m;
diff_l += i - m;
diff_r += i - m;
}
} while (is_special);
int left = -1;
if (i == r)
left = getRecursive(l, m, cnt_here - (i - m), cnt_l, cnt_r + (i - m));
else
left = getRecursive(l, m, answer[0], cnt_l, cnt_r + answer[1] + diff_r);
if (left != -1)
return left;
return getRecursive(i + 1, r, answer[1], cnt_l + answer[0] + diff_l, cnt_r);
}
int find_best(int n)
{
vector<int> cnt_here;
for (int k = 0; k < 20; k++)
{
int i = rand() % n;
vector<int> answer = ask(i);
cnt_here.push_back(answer[0] + answer[1]);
}
sort(cnt_here.begin(), cnt_here.end());
int result = getRecursive(0, n, cnt_here.back(), 0, 0);
assert(result != -1);
return result;
}
#ifdef _DEBUG
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
static const int max_q = 10000;
static int n;
static int query_count = 0;
static vector<int> g;
static vector<vector<int>> rank_count;
vector<int> ask(int i)
{
query_count++;
if (query_count > max_q)
{
cerr << "Query limit exceeded" << endl;
exit(0);
}
if (i < 0 || i >= n)
{
cerr << "Bad index: " << i << endl;
exit(0);
}
vector<int> res(2);
res[0] = rank_count[g[i] - 1][i + 1];
res[1] = rank_count[g[i] - 1][n] - res[0];
return res;
}
int main()
{
cin >> n;
g.resize(n);
for (int i = 0; i < n; i++)
{
cin >> g[i];
if (g[i] < 1)
{
cerr << "Invalid rank " << g[i] << " at index " << i << endl;
exit(0);
}
}
int max_rank = *max_element(g.begin(), g.end());
rank_count.resize(max_rank + 1, vector<int>(n + 1, 0));
for (int r = 0; r <= max_rank; r++)
{
for (int i = 1; i <= n; i++)
{
rank_count[r][i] = rank_count[r][i - 1];
if (g[i - 1] == r)
rank_count[r][i]++;
}
}
for (int i = 0; i <= n; i++)
for (int r = 1; r <= max_rank; r++)
rank_count[r][i] += rank_count[r - 1][i];
int res = find_best(n);
assert(g[res] == 1);
cout << res << endl
<< "Query count: " << query_count << endl;
return 0;
}
#endif
Compilation message
In file included from /usr/include/c++/10/cassert:44,
from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
from prize.cpp:4:
prize.cpp: In function 'int getRecursive(int, int, int, int, int)':
prize.cpp:69:24: error: 'n' was not declared in this scope
69 | assert(i >= 0 && i < n);
| ^
