anton/SummerOfCode/src/summerofcode/Day3.java

   1 package summerofcode;
   2
   3 /**
   4  *
   5  * @author Anton Dil
   6  */
   7 public class Day3
   8 {
   9    static final String pass = "the traveller in the grey riding-coat, who called himself mr. melville, was contemplating the malice of which the gods are capable.";
  10
  11    public static void main(String[] args)
  12    {
  13       part1();
  14       System.out.println("\n PART 2 ");
  15       part2();
  16    }
  17
  18    static void part2()
  19    {
  20       int[] newcode =
  21       {
  22          ci('r'), ci('i')
  23       };
  24
  25       final int alpha = 5, beta = 11;
  26
  27       System.out.printf("newcode %d %d %n", newcode[0], newcode[1]);
  28
  29       for (int i = 0; i < pass.length(); i++)
  30       {
  31          char nextCh = pass.charAt(i);
  32
  33          if (nextCh >= 'a' && nextCh <= 'z')
  34          {
  35             newcode[0] = wrap2(newcode[0] + alpha * newcode[1]);
  36             newcode[1] = wrap2(newcode[1] + beta * ci(nextCh));
  37
  38             System.out.printf("nextchar %c newcode %c %c %n", nextCh, ic(newcode[0]), ic(newcode[1]));
  39          } //else skip this char
  40
  41       }
  42    }
  43
  44    static void part1()
  45    {
  46       //assuming string length > 1
  47       int[] oldcode =
  48       {
  49          ci(pass.charAt(0)), ci(pass.charAt(1))
  50       };
  51
  52       System.out.printf("oldcode %d %d %n", oldcode[0], oldcode[1]);
  53
  54       for (int i = 2; i < pass.length(); i++)
  55       {
  56          char nextCh = pass.charAt(i);
  57
  58          if (nextCh >= 'a' && nextCh <= 'z')
  59          {
  60             //System.out.printf(" next char %c %d %n", nextCh, ci(nextCh));
  61             oldcode[0] = wrap(oldcode[0] + oldcode[1]);
  62             oldcode[1] = wrap(oldcode[1] + ci(nextCh));
  63
  64             System.out.printf("next char %c oldcode %c %c %n", nextCh, ic(oldcode[0]), ic(oldcode[1]));
  65          } //else skip this char
  66
  67       }
  68    }
  69
  70    //char conversion to int scale, 1-based
  71    static int ci(char c)
  72    {
  73       return c - 'a' + 1;
  74    }
  75
  76    //for readability, the int in char form
  77    static char ic(int x)
  78    {
  79       return (char) (x + 'a' - 1);
  80    }
  81
  82    //oldwrap only needed adjustment by 26
  83    static int wrap(int x)
  84    {
  85       if (x > 26)
  86       {
  87          return x - 26;
  88       }
  89
  90       return x;
  91    }
  92
  93    //new wrap needs a modulus
  94    static int wrap2(int x)
  95    {
  96       if (x > 26)
  97       {
  98          return (x - 1) % 26 + 1;
  99       }
 100
 101       return x;
 102    }
 103
 104 }