結果
| 問題 |
No.811 約数の個数の最大化
|
| コンテスト | |
| ユーザー |
 Pachicobue
|
| 提出日時 | 2019-04-14 20:16:45 |
| 言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
| 結果 |
AC
|
| 実行時間 | 56 ms / 2,000 ms |
| コード長 | 6,829 bytes |
| コンパイル時間 | 2,214 ms |
| コンパイル使用メモリ | 200,068 KB |
| 最終ジャッジ日時 | 2025-01-07 02:12:00 |
|
ジャッジサーバーID （参考情報） |
judge5 / judge5 |
（要ログイン）
| ファイルパターン | 結果 |
|---|---|
| sample | AC * 3 |
| other | AC * 12 |
ソースコード
#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"
#define NDEBUG
#define SHOW(...) static_cast<void>(0)
//!===========================================================!//
//! dP dP dP !//
//! 88 88 88 !//
//! 88aaaaa88a .d8888b. .d8888b. .d888b88 .d8888b. 88d888b. !//
//! 88 88 88ooood8 88' '88 88' '88 88ooood8 88' '88 !//
//! 88 88 88. ... 88. .88 88. .88 88. ... 88 !//
//! dP dP '88888P' '88888P8 '88888P8 '88888P' dP !//
//!===========================================================!//
using ld = long double;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
constexpr unsigned int MOD = 1000000007;
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 4;
template <typename F>
constexpr F PI = static_cast<F>(3.1415926535897932385);
std::mt19937 mt{std::random_device{}()};
template <typename T>
bool chmin(T& a, const T& b) { return a = std::min(a, b), a == b; }
template <typename T>
bool chmax(T& a, const T& b) { return a = std::max(a, b), a == b; }
template <typename T>
std::vector<T> Vec(const std::size_t n, T v) { return std::vector<T>(n, v); }
template <class... Args>
auto Vec(const std::size_t n, Args... args) { return std::vector<decltype(Vec(args...))>(n, Vec(args...)); }
template <typename T>
constexpr T popCount(const T u)
{
#ifdef __has_builtin
return u == 0 ? T(0) : (T)__builtin_popcountll(u);
#else
unsigned long long v = static_cast<unsigned long long>(u);
return v = (v & 0x5555555555555555ULL) + (v >> 1 & 0x5555555555555555ULL), v = (v & 0x3333333333333333ULL) + (v >> 2 & 0x3333333333333333ULL), v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL, static_cast<T>(v * 0x0101010101010101ULL >> 56 & 0x7f);
#endif
}
template <typename T>
constexpr T log2p1(const T u)
{
#ifdef __has_builtin
return u == 0 ? T(0) : T(64 - __builtin_clzll(u));
#else
unsigned long long v = static_cast<unsigned long long>(u);
return v = static_cast<unsigned long long>(v), v |= (v >> 1), v |= (v >> 2), v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32), popCount(v);
#endif
}
template <typename T>
constexpr T clog(const T v) { return v == 0 ? T(0) : log2p1(v - 1); }
template <typename T>
constexpr T msbp1(const T v) { return log2p1(v); }
template <typename T>
constexpr T lsbp1(const T v)
{
#ifdef __has_builtin
return __builtin_ffsll(v);
#else
return v == 0 ? T(0) : popCount((v & (-v)) - T(1)) + T(1);
#endif
}
template <typename T>
constexpr bool ispow2(const T v) { return popCount(v) == 1; }
template <typename T>
constexpr T ceil2(const T v) { return v == 0 ? T(1) : T(1) << log2p1(v - 1); }
template <typename T>
constexpr T floor2(const T v) { return v == 0 ? T(0) : T(1) << (log2p1(v) - 1); }
//!====================================================================================================!//
//! 888888ba oo 88888888b dP !//
//! 88 '8b 88 88 !//
//! a88aaaa8P' 88d888b. dP 88d8b.d8b. .d8888b. a88aaaa d8888b. .d8888b. d8888P .d8888b. 88d888b. !//
//! 88 88' '88 88 88''88''88 88ooood8 88 88' '88 88' '"" 88 88' '88 88' '88 !//
//! 88 88 88 88 88 88 88. ... 88 88. .88 88. ... 88 88. .88 88 !//
//! dP dP dP dP dP dP '88888P' dP '88888P8 '88888P' dP '88888P' dP !//
//!====================================================================================================!//
template <typename T>
std::vector<std::pair<T, std::size_t>> PrimeFactors(T n)
{
std::vector<std::pair<T, std::size_t>> ans;
for (T i = 2; i * i <= n; i++) {
std::size_t cnt = 0;
for (; n % i == 0; n /= i, cnt++) {}
if (cnt > 0) { ans.push_back({i, cnt}); }
}
if (n > 1) { ans.push_back({n, 1}); }
return ans;
}
//!================================================================!//
//! 888888ba oo oo !//
//! 88 '8b !//
//! 88 88 dP dP .dP dP .d8888b. .d8888b. 88d888b. .d8888b. !//
//! 88 88 88 88 d8' 88 Y8ooooo. 88' '88 88' '88 Y8ooooo. !//
//! 88 .8P 88 88 .88' 88 88 88. .88 88 88 !//
//! 8888888P dP 8888P' dP '88888P' '88888P' dP '88888P' !//
//!================================================================!//
template <typename T>
std::vector<T> Divisors(const T n)
{
std::vector<T> head, tail;
for (T i = 1; i * i <= n; i++) {
if (n % i == 0) {
head.push_back(i);
if (i * i != n) { tail.push_back(n / i); }
}
}
for (auto it = tail.rbegin(); it != tail.rend(); it++) { head.push_back(*it); }
return head;
}
//!====================================================================================!//
//! .88888. a88888b. 888888ba d88b dP a88888b. 8888ba.88ba !//
//! d8' '88 d8' '88 88 '8b 8''8 88 d8' '88 88 '8b '8b !//
//! 88 88 88 88 d8b 88 88 88 88 88 !//
//! 88 YP88 88 88 88 d8P'8b 88 88 88 88 88 !//
//! Y8. .88 Y8. .88 88 .8P d8' '8bP 88 Y8. .88 88 88 88 !//
//! '88888' Y88888P' 8888888P '888P''YP 88888888P Y88888P' dP dP dP !//
//!====================================================================================!//
template <typename T>
constexpr T gcd(const T a, const T b) { return (b != 0) ? gcd(b, a % b) : a; }
template <typename T>
constexpr T lcm(const T a, const T b) { return (a == 0 and b == 0) ? (T)0 : (a / gcd(a, b)) * b; }
//!============================================!//
//! 8888ba.88ba oo !//
//! 88 '8b '8b !//
//! 88 88 88 .d8888b. dP 88d888b. !//
//! 88 88 88 88' '88 88 88' '88 !//
//! 88 88 88 88. .88 88 88 88 !//
//! dP dP dP '88888P8 dP dP dP !//
//!============================================!//
int main()
{
int N, K;
std::cin >> N >> K;
int max = 1, ans = 0;
for (int v = 1; v < N; v++) {
const auto fac = PrimeFactors(gcd(v, N));
int i = 0;
for (const auto& p : fac) { i += p.second; }
if (i >= K) {
const int d = Divisors(v).size();
if (max < d) { max = d, ans = v; }
}
}
std::cout << ans << std::endl;
return 0;
}