| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1207075 | friendiks | Hack (APIO25_hack) | C++20 | 0 ms | 0 KiB |
#ifndef LOCAL
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC diagnostic ignored "-Wpedantic"
#endif
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
auto seed = chrono::high_resolution_clock::now().time_since_epoch().count();
mt19937_64 rnd(1488);
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename V>
using table = gp_hash_table<T, V>;
using i128 = __int128;
using ll = long long;
using ld = long double;
using uint = unsigned int;
using ull = unsigned long long;
const ll INF = 2e18;
const int inf = 2e9;
const int maxn = 1e5;
const int MOD = 988244353;
const ld pi = acos(-1);
const int P = 5167;
const int L = 26;
const ld EPS = 1e-7;
template<typename T, typename V>
void fill(T &container, V value) {
for (auto &c: container)
c = value;
}
int N;
int SUM = 0;
ll collisions(std::vector<long long> x) {
SUM += x.size();
map<ll, ll> mp;
for (auto c: x) mp[c % N]++;
ll ans = 0;
for (auto [a, b]: mp) ans += b * (b - 1) / 2;
return ans;
}
int bs = 5473;
int hack() {
ll cols = 0;
vector<ll> A(bs);
while (cols == 0) {
for (int i = 0; i < bs; ++i) A[i] = rnd() % (ll) (1e10) + 29638;
cols = collisions(A);
}
int Rpos = 0;
for (int delta = (1 << 12); delta > 0; delta /= 2) {
if (Rpos + delta > bs) continue;
vector<ll> v;
for (int i = 0; i < Rpos + delta; ++i) {
v.push_back(A[i]);
}
if (collisions(v) == 0) Rpos += delta;
}
int Lpos = Rpos;
for (int delta = (1 << 12); delta > 0; delta /= 2) {
if (Lpos - delta < 0) continue;
vector<ll> v;
for (int i = Lpos - delta + 1; i <= Rpos; ++i) {
v.push_back(A[i]);
}
if (collisions(v) == 0) Lpos -= delta;
}
ll k = abs(A[Lpos] - A[Rpos]);
ll ans = INF;
for (ll d1 = 1; d1 * d1 <= k; ++d1) {
if (k % d1 == 0) {
ll d2 = k / d1;
if (collisions({1, 1 + d1})) {
ans = min(ans, d1);
}
if (collisions({1, 1 + d2})) {
ans = min(ans, d2);
}
}
}
return ans;
}
int main() {
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
cin >> N;
cout << hack() << "\n" << SUM;
}