घुटने पर एक सौ अरब तक का डेटाबेस

class EratospheneSieve
{
    private bool[] Data;

    public EratospheneSieve(int length)
    {
        Data = new bool[length];

        for (int i = 2; i < Data.Length; i++) Data[i] = true;

        for (int i = 2; i * i < Length; i++)
        {
            if (!Data[i]) continue;
            for (int d = i * i; d < Length; d += i) Data[d] = false;
        }
    }

    public int Length => Data.Length;

    public bool IsPrime(int n) => Data[n];
}

class Wheel235
{
    private static int[] BIT_TO_INDEX = new int[] { 1, 7, 11, 13, 17, 19, 23, 29 };

    private static int[] INDEX_TO_BIT = new int[] {
        -1, 0,
        -1, -1, -1, -1, -1, 1,
        -1, -1, -1, 2,
        -1, 3,
        -1, -1, -1, 4,
        -1, 5,
        -1, -1, -1, 6,
        -1, -1, -1, -1, -1, 7,
    };

    private byte[] Data;

    public Wheel235(long length)
    {
        // ensure length divides by 30
        length = (length + 29) / 30 * 30;
        Data = new byte[length / 30];
        for (long i = 0; i < Data.Length; i++) Data[i] = byte.MaxValue;

        for (long i = 7; i * i < Length; i++)
        {
            if (!IsPrime(i)) continue;
            for (long d = i * i; d < Length; d += i) ClearPrime(d);
        }
    }

    public long Length => Data.Length * 30L;

    public bool IsPrime(long n)
    {
        if (n >= Length) throw new ArgumentException("Number too big");
        if (n <= 5) return n == 2 || n == 3 || n == 5;
        int bit = INDEX_TO_BIT[n % 30];
        if (bit < 0) return false;
        return (Data[n / 30] & (1 << bit)) != 0;
    }

    private void ClearPrime(long n)
    {
        int bit = INDEX_TO_BIT[n % 30];
        if (bit < 0) return;
        Data[n / 30] &= (byte)~(1 << bit);
    }
}

class Wheel235
{
    class LongArray
    {
        const long MAX_CHUNK_LENGTH = 2_000_000_000L;
        private byte[] firstBuffer;
        private byte[] secondBuffer;

        public LongArray(long length)
        {
            firstBuffer = new byte[Math.Min(MAX_CHUNK_LENGTH, length)];
            if (length > MAX_CHUNK_LENGTH) secondBuffer = new byte[length - MAX_CHUNK_LENGTH];
        }

        public LongArray(string file)
        {
            using(FileStream stream = File.OpenRead(file))
            {
                long length = stream.Length;
                firstBuffer = new byte[Math.Min(MAX_CHUNK_LENGTH, length)];
                if (length > MAX_CHUNK_LENGTH) secondBuffer = new byte[length - MAX_CHUNK_LENGTH];
                stream.Read(firstBuffer, 0, firstBuffer.Length);
                if(secondBuffer != null) stream.Read(secondBuffer, 0, secondBuffer.Length);
            }
        }

        public long Length => firstBuffer.LongLength + (secondBuffer == null ? 0 : secondBuffer.LongLength);

        public byte this[long index]
        {
            get => index < MAX_CHUNK_LENGTH ? firstBuffer[index] : secondBuffer[index - MAX_CHUNK_LENGTH];
            set
            {
                if (index < MAX_CHUNK_LENGTH) firstBuffer[index] = value; 
                else secondBuffer[index - MAX_CHUNK_LENGTH] = value;
            }
        }

        public void Save(string file)
        {
            using(FileStream stream = File.OpenWrite(file))
            {
                stream.Write(firstBuffer, 0, firstBuffer.Length);
                if (secondBuffer != null) stream.Write(secondBuffer, 0, secondBuffer.Length);
            }
        }

    }

    private static int[] BIT_TO_INDEX = new int[] { 1, 7, 11, 13, 17, 19, 23, 29 };

    private static int[] INDEX_TO_BIT = new int[] {
        -1, 0,
        -1, -1, -1, -1, -1, 1,
        -1, -1, -1, 2,
        -1, 3,
        -1, -1, -1, 4,
        -1, 5,
        -1, -1, -1, 6,
        -1, -1, -1, -1, -1, 7,
    };

    private LongArray Data;

    public Wheel235(long length)
    {
        // ensure length divides by 30
        length = (length + 29) / 30 * 30;
        Data = new LongArray(length / 30);
        for (long i = 0; i < Data.Length; i++) Data[i] = byte.MaxValue;

        for (long i = 7; i * i < Length; i++)
        {
            if (!IsPrime(i)) continue;
            for (long d = i * i; d < Length; d += i) ClearPrime(d);
        }
    }

    public Wheel235(string file)
    {
        Data = new LongArray(file);
    }

    public void Save(string file) => Data.Save(file);

    public long Length => Data.Length * 30L;

    public bool IsPrime(long n)
    {
        if (n >= Length) throw new ArgumentException("Number too big");
        if (n <= 5) return n == 2 || n == 3 || n == 5;
        int bit = INDEX_TO_BIT[n % 30];
        if (bit < 0) return false;
        return (Data[n / 30] & (1 << bit)) != 0;
    }

    private void ClearPrime(long n)
    {
        int bit = INDEX_TO_BIT[n % 30];
        if (bit < 0) return;
        Data[n / 30] &= (byte)~(1 << bit);
    }

}