結果

問題 No.3028 No.9999
ユーザー tobisatis
提出日時 2025-02-21 21:35:14
言語 C#
(.NET 8.0.404)
結果
AC  
実行時間 95 ms / 4,000 ms
コード長 5,481 bytes
コンパイル時間 11,800 ms
コンパイル使用メモリ 175,476 KB
実行使用メモリ 33,508 KB
最終ジャッジ日時 2025-02-21 21:35:29
合計ジャッジ時間 12,707 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge1
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 * 3
other AC * 23
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 (117 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 #
プレゼンテーションモードにする

#nullable enable
using System.Numerics;
void Run()
{
    var n = Int();
    ModInt.Mod = n;
    var ans = ((ModInt)1).DiscreteLog((ModInt)10, int.MaxValue / 2);
    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().Trim().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
interface IAdditiveGroup<T> :
    IAdditiveIdentity<T, T>,
    IAdditionOperators<T, T, T>,
    ISubtractionOperators<T, T, T>
    where T : IAdditiveGroup<T>
{
    T AdditiveInverse();
}
interface IMultiplicativeGroup<T> :
    IMultiplicativeIdentity<T, T>,
    IMultiplyOperators<T, T, T>,
    IDivisionOperators<T, T, T>
    where T : IMultiplicativeGroup<T>
{
    T MultiplicativeInverse();
}
readonly record struct ModInt :
    IEqualityOperators<ModInt, ModInt, bool>,
    IAdditiveGroup<ModInt>,
    IMultiplicativeGroup<ModInt>
{
    public static int Mod = 0;
    int V { get; init; }
    public ModInt(long value)
    {
        var v = value % Mod;
        if (v < 0) v += Mod;
        V = (int)v;
    }
    static ModInt New(int value) => new(){ V = value };
    public static implicit operator ModInt(long v) => new(v);
    public static implicit operator int(ModInt modInt) => modInt.V;
    public static ModInt AdditiveIdentity => New(0);
    public static ModInt operator +(ModInt a, ModInt b)
    {
        var v = a.V + b.V;
        if (v >= Mod) v -= Mod;
        return New(v);
    }
    public ModInt AdditiveInverse()
    {
        if (V == 0) return AdditiveIdentity;
        return New(Mod - V);
    }
    public static ModInt operator -(ModInt a, ModInt b)
    {
        var v = a.V - b.V;
        if (v < 0) v += Mod;
        return New(v);
    }
    public static ModInt MultiplicativeIdentity => New(1);
    public static ModInt operator *(ModInt a, ModInt b) => New((int)((long)a.V * b.V % Mod));
    public ModInt MultiplicativeInverse()
    {
        if (V == 0) throw new DivideByZeroException();
        var (d, x, _) = ExtendedGCD(V, Mod);
        if (d > 1) throw new DivideByZeroException();
        return x;
    }
    public static ModInt operator /(ModInt a, ModInt b) => a * b.MultiplicativeInverse();
    static long Power(long v, ulong p, long mod)
    {
        var (res, k) = (1L, v);
        while (p > 0)
        {
            if ((p & 1) > 0) res = res * k % mod;
            k = k * k % mod;
            p >>= 1;
        }
        return res;
    }
    public ModInt Power(long p) => p < 0 ? (MultiplicativeIdentity / V).Power(-p) : Power(V, (ulong)p, Mod);
    static (long d, long x, long y) ExtendedGCD(long a, long b)
    {
        var (x0, y0, x1, y1) = (1L, 0L, 0L, 1L);
        while (b != 0)
        {
            var q = a / b;
            (a, b) = (b, a - q * b);
            (x0, y0, x1, y1) = (x1, y1, x0 - q * x1, y0 - q * y1);
        }
        return (a, x0, y0);
    }
    public override string ToString() => V.ToString();
}
static class Extensions
{
    public static T[] Repeat<T>(this int time, Func<T> F) => Enumerable.Range(0, time).Select(_ => F()).ToArray();
    public static long? DiscreteLog<T>(this T a, T b, long max)
        where T : IMultiplyOperators<T, T, T>, IMultiplicativeIdentity<T, T>
    {
        var q = 1;
        while (q * q < max) q++;
        var smallSteps = new HashSet<T>();
        {
            var v = a;
            for (var i = 1; i <= q; i++)
            {
                v *= b;
                smallSteps.Add(v);
            }
        }
        var giantStep = b;
        for (var i = 2; i <= q; i++) giantStep *= b;
        var l = T.MultiplicativeIdentity;
        var yellow = false;
        for (var i = 0; i < q; i++)
        {
            var g = l * giantStep;
            if (smallSteps.Contains(g))
            {
                var v = l;
                for (var j = 1; j <= q; j++)
                {
                    v *= b;
                    if (v.Equals(a))
                    {
                        var res = (long)i * q + j;
                        if (res > max) return null;
                        return res;
                    }
                }
                if (yellow) return null;
                yellow = true;
            }
            l = g;
        }
        return null;
    }
}
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