結果

問題 No.826 連絡網
ユーザー tkmst201
提出日時 2021-02-21 16:51:09
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 5 ms / 2,000 ms
コード長 4,535 bytes
コンパイル時間 2,879 ms
コンパイル使用メモリ 201,656 KB
最終ジャッジ日時 2025-01-19 03:04:24
ジャッジサーバーID
（参考情報） 		judge5 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 30
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//
namespace tk {
std::vector<std::uint32_t> enumerate_primes(std::uint32_t n) {
    if (n < 2) return {};
    using byte = std::uint8_t;
    using uint32 = std::uint32_t;
    
    constexpr byte m[8] = {1, 7, 11, 13, 17, 19, 23, 29};
    constexpr byte diff[8] = {6, 4, 2, 4, 2, 4, 6, 2}; // [i] := m[i + 1] - m[i]
    constexpr byte plus_byte[8][8] = {
        {0,0,0,0,0,0,0,1},{1,1,1,0,1,1,1,1},{2,2,0,2,0,2,2,1},{3,1,1,2,1,1,3,1},
        {3,3,1,2,1,3,3,1},{4,2,2,2,2,2,4,1},{5,3,1,4,1,3,5,1},{6,4,2,4,2,4,6,1},
    }; // [i][j] := floor(m_i m_{j+1} / 30) - floor(m_i m_j / 30)
    constexpr byte bit_mask[8][8] = {
        {254,253,251,247,239,223,191,127},{253,223,239,254,127,247,251,191},
        {251,239,254,191,253,127,247,223},{247,254,191,223,251,253,127,239},
        {239,127,253,251,223,191,254,247},{223,247,127,253,191,254,239,251},
        {191,251,247,127,254,239,223,253},{127,191,223,239,247,251,253,254},
    }; // [i][j] := ((1<<8)-1) - (1 << to_m_idx(m[i]m[j] (mod. 30))) (mod. 8))
    
    auto pop_count = [](byte x) {
        byte res = (x & 0x55) + (x >> 1 & 0x55);
        res = (res & 0x33) + (res >> 2 & 0x33);
        res = (res + (res >> 4)) & 0xf;
        return res;
    };
    
    auto sqrt = [](uint32 n) {
        uint32 res = 0;
        for (uint32 i = sizeof(n) << 2; i > 0; --i) {
            uint32 x = res + (1u << (i - 1));
            if (x * x <= n) res |= 1u << (i - 1);
        }
        return res;
    };
    
    byte b_idx[129]; // [1 << i] = i
    for (uint32 i = 0; i < 8; ++i) b_idx[1 << i] = i;
    
    auto get_prime_pos = [&](uint32 n) {
        uint32 s = sqrt(n); // floor(sqrt(n))
        const uint32 s30 = s / 30 + (s % 30 != 0);
        const uint32 n30 = n / 30 + (n % 30 != 0);
        
        std::vector<byte> isprime(n30, 255);
        isprime[0] = 254;
        for (uint32 i = 0; i < s30; ++i) {
            for (byte j = isprime[i]; j; j &= j - 1) {
                const byte mi = b_idx[j & -j];
                byte k = mi;
                for (uint32 b = (30*i + 2*m[mi])*i + m[mi]*m[mi]/30; b < n30; b += i*diff[k] + plus_byte[mi][k], k = (k + 1) & 7)
                    isprime[b] &= bit_mask[mi][k];
            }
        }
        
        for (uint32 i = 8; i > 0; --i) {
            if ((n30 - 1) * 30 + m[i - 1] <= n) break;
            isprime.back() &= ~(1 << (i - 1));
        }
        
        uint32 cnt = 0;
        std::vector<uint32> prime_pos; // {byte} << 3 | {bit}
        for (uint32 i = 0; i < n30; ++i) {
            for (uint32 j = isprime[i]; j; j &= j - 1) {
                prime_pos.emplace_back(i << 3 | b_idx[j & -j]);
            }
        }
        return prime_pos;
    };
    
    auto prime_pos = get_prime_pos(sqrt(n));
    constexpr uint32 segment = 1 << 18;
    std::vector<uint32> pos;
    pos.reserve(prime_pos.size());
    for (uint32 i = 0; i < prime_pos.size(); ++i) {
        const uint32 pb = prime_pos[i] >> 3;
        const byte mi = prime_pos[i] & 7;
        pos.emplace_back(((30*pb + 2*m[mi])*pb + m[mi]*m[mi]/30) << 3 | mi);
    }
    
    
    const uint32 n30 = n / 30 + (n % 30 != 0);
    
    std::vector<uint32> primes;
    if (2 <= n) primes.emplace_back(2);
    if (3 <= n) primes.emplace_back(3);
    if (5 <= n) primes.emplace_back(5);
    
    std::vector<uint32> isprime;
    for (uint32 l = 0; l < n30; l += segment) {
        const uint32 d = std::min(segment, n30 - l);
        const uint32 r = l + d;
        
        isprime.assign(d, 255);
        if (l == 0) isprime[0] = 254;
        
        for (uint32 i = 0; i < prime_pos.size(); ++i) {
            const uint32 pb = prime_pos[i] >> 3;
            const byte mi = prime_pos[i] & 7;
            uint32 b = pos[i] >> 3;
            byte k = pos[i] & 7;
            while (b < d) {
                isprime[b] &= bit_mask[mi][k];
                b += pb*diff[k] + plus_byte[mi][k];
                k = (k + 1) & 7;
            }
            pos[i] = (b - d) << 3 | k;
        }
        
        for (uint32 i = 8; i > 0; --i) {
            if ((r - 1) * 30 + m[i - 1] <= n) break;
            isprime.back() &= ~(1 << (i - 1));
        }
        
        for (uint32 i = 0; i < d; ++i) {
            for (uint32 j = isprime[i]; j; j &= j - 1) primes.emplace_back((l + i) * 30 + m[b_idx[j & -j]]);
        }
    }
    return primes;
}
} // namespace tk
int main() {
    int N, P;
    cin >> N >> P;
    auto prime = tk::enumerate_primes(N);
    int cnt = 1;
    bool in = false;
    for (int p : prime) {
        in |= 2 * p <= N && P % p == 0;
        cnt += 2 * p > N;
    }
    int ans = in ? cnt : 1;
    cout << (in ? N - cnt : 1) << endl;
}
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