public static void OldSolve(int numZeros)
{
BigInteger notBouncy = 0;
BigInteger max = BigInteger.Pow(10, numZeros);
for (BigInteger num = 1; num < max; )
{
int bouncedAtIdx = 0;
char lastChar, thisChar;
string numStr = num.ToString();
if (MiscFunctions.IsBouncy(numStr, out bouncedAtIdx, out thisChar, out lastChar))
{
// go ahead and fastforward to next possible non-bouncy number
int len = numStr.Length;
string topSide, repeater;
if (thisChar > lastChar)
{
// was supposed to be going down, so next char needs to be smaller
// num=9624
// AtIdx = 3, lastChar = 2, thisChar = 4
// increment the top part to 963 and put 0's the rest of the way out
// giving 9630
BigInteger topSideBi = new BigInteger(numStr.Substring(0, bouncedAtIdx), 10);
topSideBi++;
topSide = topSideBi.ToString();
repeater = new string('0', len - bouncedAtIdx);
}
else
{
//if (bouncedAtIdx + 1 == len) continue; // it's at the 1s digit
// was supposed to be going up. So next set of chars need to be the lowest value going up
// num = 1240
// AtIdx = 3, lastChar = 4, thisChar = 0
// next char will be all 4's starting after position 3.
// giving 124 + 4 being 1244
topSide = numStr.Substring(0, bouncedAtIdx);
repeater = new string(lastChar, len - bouncedAtIdx);
}
num = new BigInteger(topSide + repeater, 10);
}
else
{
notBouncy++;
num++;
}
}
Console.WriteLine("For {0} {1}", max, notBouncy);
}
private static bool WellBalanced(BigInteger bi)
{
char[] digits = bi.ToString().ToCharArray();
int midIdx = (int)Math.Ceiling(digits.Length/(double) 2) - 1;
int maxIdx = digits.Length - 1;
int left = 0;
int right = 0;
//int idxLeft = midIdx;
//int idxRight = digits.Length - midIdx - 1;
for (int i = 0; i <= midIdx ;i++ )
{
left += (int)digits[i];
right += (int)digits[maxIdx - i];
}
return left==right;
}
public static string GetSequence(BigInteger num, BigInteger denom)
{
Console.WriteLine("\tBEFORE {0} {1}", num,denom);
MyMath.ReduceFraction(ref num, ref denom);
Console.WriteLine("\tAFTER {0} {1}", num, denom);
return "";
int decimalsOfPrecision = 0;
Int32.TryParse(denom.ToString(),out decimalsOfPrecision);
decimalsOfPrecision *= 2;
decimalsOfPrecision = Math.Max(5, decimalsOfPrecision);
//BigInteger offset = BigInteger.Parse("1" + Repeat('0', decimalsOfPrecision)); // use offset to get n decimals of precision
BigInteger offset = BigInteger.Pow(10, decimalsOfPrecision);
Console.WriteLine("decimalsOfPrecision={0}", decimalsOfPrecision);
BigInteger fraction = offset * num / denom;
string unitFraction = fraction.ToString();
unitFraction = Repeat('0', decimalsOfPrecision - unitFraction.Length) + unitFraction;
string sequence = GetRepeatingElement(unitFraction);
return (sequence=="0")?"":sequence;
}
/// <summary>
/// Tests the correct implementation of the modulo exponential function
/// using RSA encryption and decryption (using pre-computed encryption and
/// decryption keys).
/// </summary>
/// <param name="rounds">The rounds.</param>
public static void RSATest(int rounds)
{
Random rand = new Random(1);
byte[] val = new byte[64];
// private and public key
BigInteger bi_e = new BigInteger("a932b948feed4fb2b692609bd22164fc9edb59fae7880cc1eaff7b3c9626b7e5b241c27a974833b2622ebe09beb451917663d47232488f23a117fc97720f1e7", 16);
BigInteger bi_d = new BigInteger("4adf2f7a89da93248509347d2ae506d683dd3a16357e859a980c4f77a4e2f7a01fae289f13a851df6e9db5adaa60bfd2b162bbbe31f7c8f828261a6839311929d2cef4f864dde65e556ce43c89bbbf9f1ac5511315847ce9cc8dc92470a747b8792d6a83b0092d2e5ebaf852c85cacf34278efa99160f2f8aa7ee7214de07b7", 16);
BigInteger bi_n = new BigInteger("e8e77781f36a7b3188d711c2190b560f205a52391b3479cdb99fa010745cbeba5f2adc08e1de6bf38398a0487c4a73610d94ec36f17f3f46ad75e17bc1adfec99839589f45f95ccc94cb2a5c500b477eb3323d8cfab0c8458c96f0147a45d27e45a4d11d54d77684f65d48f15fafcc1ba208e71e921b9bd9017c16a5231af7f", 16);
Console.WriteLine("e =\n" + bi_e.ToString(10));
Console.WriteLine("\nd =\n" + bi_d.ToString(10));
Console.WriteLine("\nn =\n" + bi_n.ToString(10) + "\n");
for (int count = 0; count < rounds; count++)
{
// generate data of random length
int t1 = 0;
while (t1 == 0)
t1 = (int)(rand.NextDouble() * 65);
bool done = false;
while (!done)
{
for (int i = 0; i < 64; i++)
{
if (i < t1)
val[i] = (byte)(rand.NextDouble() * 256);
else
val[i] = 0;
if (val[i] != 0)
done = true;
}
}
while (val[0] == 0)
val[0] = (byte)(rand.NextDouble() * 256);
Console.Write("Round = " + count);
// encrypt and decrypt data
BigInteger bi_data = new BigInteger(val, t1);
BigInteger bi_encrypted = bi_data.modPow(bi_e, bi_n);
BigInteger bi_decrypted = bi_encrypted.modPow(bi_d, bi_n);
// compare
if (bi_decrypted != bi_data)
{
Console.WriteLine("\nError at round " + count);
Console.WriteLine(bi_data + "\n");
return;
}
Console.WriteLine(" <PASSED>.");
}
}
public static BigInteger Reverse(BigInteger num)
{
string reversed = String.Empty;
foreach (char c in num.ToString())
{
reversed = c.ToString() + reversed;
}
return new BigInteger(reversed,10);
}
//public static bool IsNotBouncy(int num)
//{
// char[] digits = num.ToString().ToCharArray();
// int lastDigit = Int32.Parse(digits[0].ToString());
// bool wentUp = false;
// bool wentDn = false;
// foreach (char c in digits)
// {
// int thisDigit = Int32.Parse(c.ToString());
// if (thisDigit > lastDigit)
// wentUp = true;
// if (thisDigit < lastDigit)
// wentDn = true;
// if (wentUp && wentDn)
// {
// return false;
// }
// lastDigit = thisDigit;
// }
// return (wentUp && wentDn);
//}
//public static bool IsBouncy(int num)
//{
// char[] digits = num.ToString().ToCharArray();
// int lastDigit = Int32.Parse(digits[0].ToString());
// bool wentUp = false;
// bool wentDn = false;
// foreach (char c in digits)
// {
// int thisDigit = Int32.Parse(c.ToString());
// if (thisDigit > lastDigit)
// wentUp = true;
// if (thisDigit < lastDigit)
// wentDn = true;
// if (wentUp && wentDn)
// {
// break;
// }
// lastDigit = thisDigit;
// }
// return (wentUp && wentDn);
//}
public static int SumDigits(BigInteger num)
{
int sum = 0;
foreach ( char c in num.ToString( ).ToCharArray( ) )
{
sum += Int32.Parse(c.ToString());
}
return sum;
}
public static int SumDigits(BigInteger value)
{
return SumDigits(value.ToString());
}
