結果

問題 No.8079 アルベド
ユーザー nonamae
提出日時 2022-07-12 12:45:48
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 541 ms / 2,000 ms
コード長 1,827 bytes
コンパイル時間 2,484 ms
コンパイル使用メモリ 200,268 KB
最終ジャッジ日時 2025-01-30 06:43:05
ジャッジサーバーID
（参考情報） 		judge3 / judge5
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ファイルパターン 結果
other AC * 10
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;
using u64 = uint_fast64_t;
u64 count_primes(const u64 n) {
    if (n <= 1) return 0;
    if (n == 2) return 1;
    const int sq = sqrtl(n);
    int s = 1 + sq >> 1;
    vector<int> smalls(s); for (int i = 1; i < s; ++i) smalls[i] = i;
    vector<int> roughs(s); for (int i = 0; i < s; ++i) roughs[i] = i << 1 | 1;
    vector<u64> larges(s); for (int i = 0; i < s; ++i) larges[i] = (n / (i << 1 | 1) - 1) >> 1;
    vector<bool> skip(sq + 1);
    const auto divide = [] (u64 n, u64 d) -> int { return (long double) n / d; };
    const auto half = [](int n) -> int { return (n - 1) >> 1; };
    int pc = 0;
    for (int p = 3; p <= sq; p += 2) if (!skip[p]) {
        int q = p * p;
        if ((u64) q * q > n) break;
        skip[p] = true;
        for (int i = q; i <= sq; i += p << 1) skip[i] = true;
        int ns = 0;
        for (int k = 0; k < s; k++) {
            int i = roughs[k];
            if (skip[i]) continue;
            u64 d = (u64)i * p;
            larges[ns] = larges[k] - (d <= sq ? larges[smalls[d >> 1] - pc] : smalls[half(divide(n, d))]) + pc;
            roughs[ns++] = i;
        }
        s = ns;
        for (int i = half(sq), j = ((sq / p) - 1) | 1; j >= p; j -= 2) {
            int c = smalls[j >> 1] - pc;
            for (int e = (j * p) >> 1; i >= e; --i) smalls[i] -= c;
        }
        pc++;
    }
    larges[0] += (u64)(s + 2 * (pc - 1)) * (s - 1) / 2;
    for (int k = 1; k < s; k++) larges[0] -= larges[k];
    for (int l = 1; l < s; l++) {
        int q = roughs[l];
        u64 m = n / q;
        int e = smalls[half(m / q)] - pc;
        if (e < l + 1) break;
        u64 t = 0;
        for (int k = l + 1; k <= e; k++) t += smalls[half(divide(m, roughs[k]))];
        larges[0] += t - (u64) (e - l) * (pc + l - 1);
    }
    return larges[0] + 1;
}
int main() {
    u64 a, b;
    cin >> a;
    while (a--) {
        cin >> b;
        cout << count_primes(b) << '\n';
    }
}
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