結果

問題 No.3127 Multiple of Twin Prime
ユーザー tobisatis
提出日時 2025-04-25 21:39:54
言語 C#
(.NET 8.0.404)
結果
AC  
実行時間 504 ms / 2,500 ms
コード長 4,222 bytes
コンパイル時間 8,729 ms
コンパイル使用メモリ 172,144 KB
実行使用メモリ 266,020 KB
最終ジャッジ日時 2025-04-25 21:40:26
合計ジャッジ時間 16,192 ms
ジャッジサーバーID
（参考情報） 		judge4 / 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 * 1
other AC * 12
権限があれば一括ダウンロードができます
コンパイルメッセージ
  復元対象のプロジェクトを決定しています...
  /home/judge/data/code/main.csproj を復元しました (102 ミリ秒)。
  main -> /home/judge/data/code/bin/Release/net8.0/main.dll
  main -> /home/judge/data/code/bin/Release/net8.0/publish/

ソースコード

diff # 

#nullable enable

using System.Numerics;

void Run()
{
    var t = Int();
    var qz = new (long, int)[t].AsSpan();
    for (var i = 0; i < t; i++) qz[i] = (long.Parse(String()), i);
    qz.Sort();
    var prime = new Prime(10001000).Primes;
    var ans = new long[t];
    var l = 15L;
    var pi = 2;
    (long, bool) Next()
    {
        var p1 = prime[pi + 1];
        var p2 = prime[pi];
        return ((long)p1 * p2, p1 - p2 == 2);
    }
    foreach (var (n, i) in qz)
    {
        if (n < 15)
        {
            ans[i] = -1;
            continue;
        }
        while (true)
        {
            var (next, f) = Next();
            if (next > n) break;
            pi++;
            if (f) l = next;
        }
        ans[i] = l;
    }
    Out(ans);
}

#region
AtCoderIO _io_;
var _backend_ = new StandardIOBackend();
_io_ = new(){ Backend = _backend_ };
Run();
_backend_.Flush();

string String() => _io_.Next();
int Int() => int.Parse(String());
void Out(object? x, string? sep = null) => _io_.Out(x, sep);

class AtCoderIO
{
    public required StandardIOBackend Backend { get; init; }

    Memory<string> _input = Array.Empty<string>();
    int _iter = 0;
    public string Next()
    {
        while (_iter >= _input.Length) (_input, _iter) = (Backend.ReadLine().Split(' '), 0);
        return _input.Span[_iter++];
    }

    public void Out(object? x, string? separator = null)
    {
        if (x == null) return;
        separator ??= Environment.NewLine;
        if (x is System.Collections.IEnumerable a and not string)
        {
            var objects = a.Cast<object>();
            if (separator == Environment.NewLine && !objects.Any()) return;
            x = string.Join(separator, objects);
        }
        Backend.WriteLine(x);
    }
}

class StandardIOBackend
{
    readonly StreamReader _sr = new(Console.OpenStandardInput());
    readonly StreamWriter _sw = new(Console.OpenStandardOutput()) { AutoFlush = false };
    public string ReadLine() => _sr.ReadLine()!;
    public void WriteLine(object? value) => _sw.WriteLine(value);
    public void Flush() => _sw.Flush();
}
#endregion

static class Extensions
{
    public static T[] Repeat<T>(this int time, Func<T> F) => Enumerable.Range(0, time).Select(_ => F()).ToArray();
}

class Prime
{
    readonly int[] sieve;
    public readonly List<int> Primes = new();

    public Prime(int n)
    {
        if (n <= 3) n = 3;
        sieve = new int[n + 1];
        var (d, i, primes) = (2, 5, Primes);
        primes.Add(2);
        primes.Add(3);
        var span = sieve.AsSpan();
        span[1] = 1;
        for (var j = 2; j <= n; j += 2) span[j] = 2;
        for (var j = 3; j <= n; j += 3) span[j] = 3;
        while (i <= n)
        {
            if (span[i] == 0)
            {
                primes.Add(i);
                for (var j = i; j <= n; j += i) span[j] = i;
            }
            i += d;
            d ^= 6;
        }
    }

    public bool IsPrime(int x)
    {
        if (x < 2) return false;
        if (x < sieve.Length) return sieve[x] == x;
        foreach (long p in Primes)
        {
            if (p * p > x) return true;
            if (x % p == 0) return false;
        }
        throw new Exception();
    }

    // descending
    public List<int> Factorize(int x)
    {
        var factors = new List<int>();
        while (sieve[x] > 1) { factors.Add(sieve[x]); x /= sieve[x]; }
        return factors;
    }

    public List<int> Divisors(int x)
    {
        var factors = Factorize(x);
        var powerLists = new List<List<int>>();
        var last = 1;
        foreach (var factor in factors)
        {
            if (factor != last)
            {
                powerLists.Add(new List<int>(new int[] { 1 }));
                last = factor;
            }
            var powers = powerLists[^1];
            powers.Add(powers[^1] * factor);
        }
        var divisors = new List<int>();
        void Enumerate(int index, int divisor)
        {
            if (index == powerLists.Count) { divisors.Add(divisor); return; }
            foreach (var power in powerLists[index]) Enumerate(index + 1, divisor * power);
        }
        Enumerate(0, 1);
        return divisors;
    }
}
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