#1194705 (C#) No.3777 Train Seats

• 問題: No.3777 Train Seats
• ユーザー: tobisatis
• 提出日時: 2026-10-23 22:50:27
• 言語: C# (.NET 10.0.402 + ACL)
• 結果: WA
• 実行時間: -
• コード長: 7,064 bytes
• コンパイル時間: 13,410 ms
• コンパイル使用メモリ: 173,436 KB
• 実行使用メモリ: 40,064 KB
• 最終ジャッジ日時: 2026-10-23 22:50:48
• 合計ジャッジ時間: 20,745 ms
• ジャッジサーバーID （参考情報）: judge1_0 / judge5_0

ファイルパターン	結果
sample	AC * 3
other	AC * 2 WA * 48

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 (281 ミリ秒)。
  main -> /home/judge/data/code/bin/Release/net10.0/main.dll
  main -> /home/judge/data/code/bin/Release/net10.0/publish/

ソースコード

#nullable enable

var n = int.Parse(Console.ReadLine()!);

var mod = (int)FPSNTT.Mod;
FPSNTT.MaxLength = n + 2;
var f0 = new FPSNTT();
f0[0] = f0[1] = 1;
var f = new FPSNTT();
f[1] = f[2] = 1;
var fac = new long[n + 1];
fac[0] = 1;
for (var i = 1; i <= n; i++) fac[i] = fac[i - 1] * i % mod;
// {
//     var t = 1L;
//     for (var i = 1; i <= n; i++)
//     {
//         f[i] = t;
//         f.DivAt(i, fac[i]);
//         t = t * 2 % mod;
//     }
// }
var ans = 0L;
var g = f0 * f0;
for (var k = 1; k <= n; k++)
{
    ans += g[n - k] * fac[n - k] % mod * fac[k] % mod;
    g *= f;
}
Console.WriteLine(ans);

class FPSNTT
{
    public static int MaxLength = -6;
    public const uint Mod = (1 << P) * K + 1;
    const int P = 23;
    const int K = 119;
    const int R = 3;
    uint[] _data = [0];
    int _length = 1;

    public FPSNTT() { }
    public static FPSNTT From(ReadOnlySpan<long> a)
    {
        var res = new FPSNTT();
        for (var i = 0; i < a.Length; i++) res[i] = a[i];
        return res;
    }

    public long this[int i]
    {
        get => i < _length ? _data[i] : 0;
        set
        {
            Resize(i);
            _data[i] = Rem(value);
        }
    }
    public long[] Slice(int start, int length)
    {
        var res = new long[length];
        for (var i = 0; i < length; i++) res[i] = this[start + i];
        return res;
    }

    public static FPSNTT operator *(FPSNTT f, long k)
    {
        k = Rem(k);
        var a = new uint[f._data.Length];
        for (var i = 0; i < f._length; i++) a[i] = (uint)(f[i] * k % Mod);
        return new(a, f._length);
    }
    public static FPSNTT operator /(FPSNTT f, long k) => f * Pow(k, -1);
    public void DivAt(int i, long k) => this[i] *= Pow(k, -1);

    public static FPSNTT AdditiveIdentity => new([0]);
    public static FPSNTT operator +(FPSNTT l, FPSNTT r)
    {
        if (l._length < r._length) (l, r) = (r, l);
        var (llen, rlen) = (l._length, r._length);
        var a = new uint[l._data.Length];
        for (var i = 0; i < rlen; i++) a[i] = (uint)(l[i] + r[i]) % Mod;
        for (var i = rlen; i < llen; i++) a[i] = (uint)l[i];
        return new(a, llen);
    }
    public FPSNTT AdditiveInverse() => this * -1;
    public static FPSNTT operator -(FPSNTT l, FPSNTT r) => l + r * -1;

    public static FPSNTT MultiplicativeIdentity => new([1]);
    public static FPSNTT operator *(FPSNTT f, FPSNTT g) => new(Mul(f.ToSpan(), g.ToSpan()), f._length + g._length - 1);
    public FPSNTT MultiplicativeInverse()
    {
        if (_data[0] == 0) throw new Exception("the constant term must not be zero");
        return new(Inv(ToSpan(), MaxLength));
    }
    public static FPSNTT operator /(FPSNTT l, FPSNTT r) => l * r.MultiplicativeInverse();

    ReadOnlySpan<uint> ToSpan() => _data.AsSpan()[.._length];
    void Resize(int idx)
    {
        _length = Math.Max(_length, idx + 1);
        var len = _data.Length;
        if (idx < len) return;
        if (idx >= MaxLength) throw new IndexOutOfRangeException();
        var len2 = len;
        while (idx >= len2) len2 <<= 1;
        var (data, data2) = (_data, new uint[len2]);
        for (var i = 0; i < len; i++) data2[i] = data[i];
        _data = data2;
    }

    static uint[] Expanded(ReadOnlySpan<uint> data, int level)
    {
        var res = new uint[1 << level];
        data.CopyTo(res);
        return res;
    }

    FPSNTT(uint[] data, int length) { _data = data; _length = Math.Min(length, MaxLength); }
    FPSNTT(uint[] data) { _data = data; _length = Math.Min(data.Length, MaxLength); }
    static uint Rem(long v)
    {
        var res = v % Mod;
        return (uint)(res < 0 ? res + Mod : res);
    }
    static uint Pow(long n, long m)
    {
        if (m < 0) m = (m % (Mod - 1)) + Mod - 1;
        var (res, k) = (1L, n);
        while (m > 0)
        {
            if ((m & 1) > 0) res = res * k % Mod;
            k = k * k % Mod;
            m >>= 1;
        }
        return Rem(res);
    }

    static readonly ulong[] _r1, _r2;
    static readonly int[][] _butterfly;

    static FPSNTT()
    {
        var r1 = new ulong[P + 1];
        var r2 = new ulong[P + 1];
        var u = Pow(R, K);
        (r1[P], r2[P]) = (u, Pow(u, -1));
        for (var i = P; i > 0; i--)
        {
            r1[i - 1] = r1[i] * r1[i] % Mod;
            r2[i - 1] = r2[i] * r2[i] % Mod;
        }
        (_r1, _r2, _butterfly) = (r1, r2, new int[P + 1][]);
    }

    static int[] Butterfly(int level)
    {
        if (_butterfly[level] != null) return _butterfly[level];
        var n = 1 << level;
        var b = new int[n];
        for (int p = 1, d = n >> 1; p < n; p <<= 1, d >>= 1) for (var k = 0; k < p; ++k) b[k | p] = b[k] | d;
        return _butterfly[level] = b;
    }

    static void FastModuloTransform(Span<uint> f, int level, bool reverse)
    {
        var n = f.Length;
        if (n < 2) return;
        var b = Butterfly(level);
        for (var i = 0; i < n; i++)
        {
            var j = b[i];
            if (i < j) (f[i], f[j]) = (f[j], f[i]);
        }
        var rotations = reverse ? _r1 : _r2;
        for (var k = 1; k <= level; k++)
        {
            var l = 1 << k;
            var h = l >> 1;
            var root = rotations[k];
            for (var i = 0; i < n; i += l)
            {
                var rotation = 1UL;
                for (var j = 0; j < h; j++)
                {
                    var (ui, vi) = (i + j, i + j + h);
                    var (u, v) = (f[ui], (uint)(f[vi] * rotation % Mod));
                    (f[ui], f[vi]) = ((u + v) % Mod, (Mod + u - v) % Mod);
                    rotation = rotation * root % Mod;
                }
            }
        }
    }

    static uint[] Mul(ReadOnlySpan<uint> f, ReadOnlySpan<uint> g, int len = -1)
    {
        if (len < 0) len = f.Length + g.Length - 1;
        var (n, level) = (1, 0);
        while (n < len) (n, level) = (n << 1, level + 1);
        var ft = Expanded(f, level);
        var gt = Expanded(g, level);
        FastModuloTransform(ft, level, false);
        FastModuloTransform(gt, level, false);
        for (var i = 0; i < n; i++) ft[i] = (uint)((ulong)ft[i] * gt[i] % Mod);
        FastModuloTransform(ft, level, true);
        var nInverse = Pow(n, -1);
        for (var i = 0; i < len; i++) ft[i] = (uint)((ulong)ft[i] * nInverse % Mod);
        for (var i = len; i < n; i++) ft[i] = 0;
        return ft;
    }

    static uint[] InvStep(ReadOnlySpan<uint> f, ReadOnlySpan<uint> g)
    {
        var l1 = g.Length;
        var l2 = l1 << 1;
        var flen = Math.Min(f.Length, l2);
        var h = Mul(f[..flen], g, l2);
        h.AsSpan()[..l1].Clear();
        h = Mul(h, g, l2);
        for (var i = 0; i < l1; i++) h[i] = g[i];
        for (var i = l1; i < l2; i++) h[i] = (Mod - h[i]) % Mod;
        return h;
    }

    static uint[] Inv(ReadOnlySpan<uint> f, int tl)
    {
        var g = new[]{ Pow(f[0], -1) };
        if (f.Length == 1) return g;
        while (g.Length < tl) g = InvStep(f, g);
        return g;
    }
}