/// <summary>
/// https://projecteuler.net/problem=59
/// </summary>
/// <param name="arguments"></param>
/// <returns></returns>
public static Result XorDecryption(Problem arguments)
{
const char FirstChar = 'a';
const char LastChar = 'z';
var sum = 0;
var key = string.Empty;
var text = string.Empty;
var cvsinfo = arguments.Sequence.Split('|');
var fileName = cvsinfo[0];
var delimiter = Convert.ToChar(cvsinfo[1]);
var qualifier = Convert.ToChar(cvsinfo[2]);
var cyphers = UtilityFile.ReadCsvToArray(fileName, delimiter, qualifier);
var ascii = cyphers.Select(X => Convert.ToInt32(X)).ToArray();
var allPossiblePasswords = (from a in FirstChar.To(LastChar)
from b in FirstChar.To(LastChar)
from c in FirstChar.To(LastChar)
select new[] { Convert.ToInt32(a), Convert.ToInt32(b), Convert.ToInt32(c) }).ToArray();
foreach (var password in allPossiblePasswords)
{
var decrypted = UtilityMath.Encrypt(ascii, password);
text = new string(decrypted.Select(x => Convert.ToChar(x)).ToArray());
if (text.Contains(" the ")) //perform simple check: if Text contains single word 'the' it is in english
{
key = new string(password.Select(x => Convert.ToChar(x)).ToArray());
break;
}
}
sum = text.Aggregate(0, (runningTotal, next) => runningTotal += next);
var answer = sum.ToString();
var message = string.Format("The sum of the ASCII values in the original English text is {0}.", answer);
if (Answers[arguments.Id] != answer)
{
message += string.Format(" => INCORRECT ({0})", Answers[arguments.Id]);
}
var r = new Result(arguments.Id, message)
{
Answer = answer
};
return(r);
}
////////////////////////////////////////////////////////////////////
// Write object to PDF file
////////////////////////////////////////////////////////////////////
internal override void WriteObjectToPdfFile
(
BinaryWriter PdfFile
)
{
// look for first and last character
Int32 FirstChar;
Int32 LastChar;
for (FirstChar = 0; FirstChar < 256 && !ActiveChar[FirstChar]; FirstChar++)
{
;
}
if (FirstChar == 256)
{
return;
}
for (LastChar = 255; !ActiveChar[LastChar]; LastChar--)
{
;
}
// pdf font name
StringBuilder PdfFontName = new StringBuilder("/");
// for embedded font add 6 alpha characters prefix
if (EmbeddedFont)
{
PdfFontName.Append("PFWAAA+");
Int32 Ptr1 = 6;
for (Int32 Ptr2 = ResourceCode.Length - 1; Ptr2 >= 0 && Char.IsDigit(ResourceCode[Ptr2]); Ptr2--)
{
PdfFontName[Ptr1--] = (Char)((Int32)ResourceCode[Ptr2] + ('A' - '0'));
}
}
// PDF readers are not happy with space in font name
PdfFontName.Append(FontFamily.Name.Replace(" ", "#20"));
// font name
if ((DesignFont.Style & FontStyle.Bold) != 0)
{
if ((DesignFont.Style & FontStyle.Italic) != 0)
{
PdfFontName.Append(",BoldItalic");
}
else
{
PdfFontName.Append(",Bold");
}
}
else if ((DesignFont.Style & FontStyle.Italic) != 0)
{
PdfFontName.Append(",Italic");
}
// add items to dictionary
AddToDictionary("/Subtype", "/TrueType");
AddToDictionary("/BaseFont", PdfFontName.ToString());
// add first and last characters
AddToDictionary("/FirstChar", FirstChar.ToString());
AddToDictionary("/LastChar", LastChar.ToString());
// create font descriptor
FontDescriptor = new PdfObject(Document, false, "/FontDescriptor");
// add link to font object
AddToDictionary("/FontDescriptor", FontDescriptor);
// font descriptor dictionary
FontDescriptor.AddToDictionary("/FontName", PdfFontName.ToString()); // must be the same as BaseFont above
FontDescriptor.AddToDictionary("/Flags", ((Int32)FontFlags).ToString());
FontDescriptor.AddToDictionary("/ItalicAngle", String.Format(NFI.DecSep, "{0}", (Single)PdfItalicAngle));
FontDescriptor.AddToDictionary("/FontWeight", PdfFontWeight.ToString());
FontDescriptor.AddToDictionary("/Leading", String.Format(NFI.DecSep, "{0}", (Single)FontUnitsToPdfDic(PdfLeading)));
FontDescriptor.AddToDictionary("/Ascent", String.Format(NFI.DecSep, "{0}", (Single)FontUnitsToPdfDic(PdfAscent)));
FontDescriptor.AddToDictionary("/Descent", String.Format(NFI.DecSep, "{0}", (Single)FontUnitsToPdfDic(-PdfDescent)));
// alphabetic (non symbolic) fonts
if ((FontFlags & PdfFontFlags.Symbolic) == 0)
{
AddToDictionary("/Encoding", "/WinAnsiEncoding");
BoundingBox Box = FontInfo.GetGlyphMetricsApi('x');
FontDescriptor.AddToDictionary("/XHeight", String.Format(NFI.DecSep, "{0}", (Single)FontUnitsToPdfDic(Box.Rect.Top)));
FontDescriptor.AddToDictionary("/AvgWidth", String.Format(NFI.DecSep, "{0}", (Single)FontUnitsToPdfDic(Box.Width)));
Box = FontInfo.GetGlyphMetricsApi('M');
PdfCapHeight = Box.Rect.Top;
FontDescriptor.AddToDictionary("/CapHeight", String.Format(NFI.DecSep, "{0}", (Single)FontUnitsToPdfDic(Box.Rect.Top)));
FontDescriptor.AddToDictionary("/StemV", String.Format(NFI.DecSep, "{0}", (Single)StemV()));
}
// create width object array
FontWidthArray = new PdfObject(Document, false);
// add link to font object
AddToDictionary("/Widths", FontWidthArray);
// build bounding box and width array
Double Left = Double.MaxValue;
Double Bottom = Double.MaxValue;
Double Right = Double.MinValue;
Double Top = Double.MinValue;
Double MaxWidth = Double.MinValue;
FontWidthArray.ContentsString = new StringBuilder("[");
Int32 EolLength = 100;
for (Int32 Index = FirstChar; Index <= LastChar; Index++)
{
Double CharWidth;
// not used
if (!ActiveChar[Index])
{
CharWidth = 0;
}
// used
else
{
// bounding box
BoundingBox GM = GlyphArray[Index];
if (GM.Rect.Left < Left)
{
Left = GM.Rect.Left;
}
if (GM.Rect.Bottom < Bottom)
{
Bottom = GM.Rect.Bottom;
}
if (GM.Rect.Right > Right)
{
Right = GM.Rect.Right;
}
if (GM.Rect.Top > Top)
{
Top = GM.Rect.Top;
}
// character advance width
CharWidth = GM.Width;
// max width
if (CharWidth > MaxWidth)
{
MaxWidth = CharWidth;
}
}
// add width to width array
if (FontWidthArray.ContentsString.Length > EolLength)
{
FontWidthArray.ContentsString.Append('\n');
EolLength = FontWidthArray.ContentsString.Length + 100;
}
// add width to width array
FontWidthArray.ContentsString.AppendFormat(NFI.DecSep, "{0} ", FontUnitsToPdfDic(CharWidth));
}
// add to font descriptor array
FontDescriptor.AddToDictionary("/MaxWidth", String.Format(NFI.DecSep, "{0}", (Single)FontUnitsToPdfDic(MaxWidth)));
FontDescriptor.AddToDictionary("/FontBBox", String.Format(NFI.DecSep, "[{0} {1} {2} {3}]",
FontUnitsToPdfDic(Left), FontUnitsToPdfDic(Bottom), FontUnitsToPdfDic(Right), FontUnitsToPdfDic(Top)));
// terminate width array
FontWidthArray.ContentsString.Length--;
FontWidthArray.ContentsString.Append("]");
// create font file
if (EmbeddedFont)
{
// create font file stream
PdfFontFile EmbeddedFontObj = new PdfFontFile(this);
// add link to font object
FontDescriptor.AddToDictionary("/FontFile2", EmbeddedFontObj);
}
// call base write PdfObject to file method
base.WriteObjectToPdfFile(PdfFile);
// exit
return;
}
