#381639 (C++17) No.888 約数の総和

• 問題: No.888 約数の総和
• ユーザー: kimiyuki
• 提出日時: 2019-09-20 22:27:55
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 14 ms / 2,000 ms
• コード長: 2,415 bytes
• コンパイル時間: 2,315 ms
• コンパイル使用メモリ: 199,664 KB
• 最終ジャッジ日時: 2025-01-07 18:45:42
• ジャッジサーバーID （参考情報）: judge5 / judge3

ファイルパターン	結果
sample	AC * 3
other	AC * 30

ソースコード

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#include <bits/stdc++.h>
#define REP(i, n) for (int i = 0; (i) < (int)(n); ++ (i))
#define REP3(i, m, n) for (int i = (m); (i) < (int)(n); ++ (i))
#define REP_R(i, n) for (int i = (int)(n) - 1; (i) >= 0; -- (i))
#define REP3R(i, m, n) for (int i = (int)(n) - 1; (i) >= (int)(m); -- (i))
#define ALL(x) begin(x), end(x)
using namespace std;
/**
 * @note O(\sqrt{n})
 * @note about 1.0 sec for 10^5 queries with n < 10^10
 */
struct prepared_primes {
    int size;
    vector<int> sieve;
    vector<int> primes;
    prepared_primes(int size_)
        : size(size_) {
        sieve.resize(size);
        REP3 (p, 2, size) if (sieve[p] == 0) {
            primes.push_back(p);
            for (int k = p; k < size; k += p) {
                if (sieve[k] == 0) {
                    sieve[k] = p;
                }
            }
        }
    }
    vector<int64_t> prime_factorize(int64_t n) {
        assert (1 <= n and n < (int64_t)size * size);
        vector<int64_t> result;
        // trial division for large part
        for (int p : primes) {
            if (n < size or n < (int64_t)p * p) {
                break;
            }
            while (n % p == 0) {
                n /= p;
                result.push_back(p);
            }
        }
        // small part
        if (n == 1) {
            // nop
        } else if (n < size) {
            while (n != 1) {
                result.push_back(sieve[n]);
                n /= sieve[n];
            }
        } else {
            result.push_back(n);
        }
        assert (is_sorted(ALL(result)));
        return result;
    }
    bool is_prime(int64_t n) {
        return prime_factorize(n).size() == 1;
    }
    vector<int64_t> list_all_factors(int64_t n) {
        auto p = prime_factorize(n);
        vector<int64_t> d;
        d.push_back(1);
        for (int l = 0; l < p.size(); ) {
            int r = l + 1;
            while (r < p.size() and p[r] == p[l]) ++ r;
            int n = d.size();
            REP (k1, r - l) {
                REP (k2, n) {
                    d.push_back(d[d.size() - n] * p[l]);
                }
            }
            l = r;
        }
        return d;
    }
};
int64_t solve(int64_t n) {
    prepared_primes primes(sqrt(n) + 3);
    auto factors = primes.list_all_factors(n);
    return accumulate(ALL(factors), 0ll);
}
int main() {
    int64_t n; cin >> n;
    cout << solve(n) << endl;
}
 
 
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