03-door-codes/day3.dart

   1 int o(String char) {
   2   return char.codeUnitAt(0) - 'a'.codeUnitAt(0) + 1;
   3 }
   4
   5 int n(int rune) {
   6   return rune - 'a'.codeUnitAt(0) + 1;
   7 }
   8
   9
  10 String c(int num) {
  11   return new String.fromCharCode((num - 1) % 26 + 'a'.codeUnitAt(0));
  12 }
  13
  14 var letters = new RegExp(r'[a-z]');
  15
  16 String code1(String expanded_passphrase) {
  17   String passphrase = letters.allMatches(expanded_passphrase).map((Match m) => m[0]).join();
  18   String c0 = passphrase[0];
  19   String c1 = passphrase[1];
  20   passphrase.substring(2).runes.forEach((int rune) {
  21     c0 = c(o(c0) + o(c1));
  22     c1 = c(o(c1) + n(rune));
  23   });
  24   return c0 + c1;
  25 }
  26
  27 String code2(String expanded_passphrase) {
  28   String passphrase = letters.allMatches(expanded_passphrase).map((Match m) => m[0]).join();
  29   int alpha = 5;
  30   int beta = 11;
  31   String c0 = "r";
  32   String c1 = "i";
  33   passphrase.runes.forEach((int rune) {
  34     c0 = c(o(c0) + o(c1) * alpha);
  35     c1 = c(o(c1) + n(rune) * beta);
  36   });
  37   return c0 + c1;
  38 }
  39
  40 void main() {
  41 //   "abcdefghijklmnopqrstuvwxyz".runes.forEach((int rune) {
  42 //     print('$rune : ${new String.fromCharCode(rune)} :: ${n(rune)} ${c(n(rune) + 28)}');
  43 //   });
  44
  45 //   for (var match in letters.allMatches('The quick ! broWn')) {
  46 //      print(match.group(0)); // 15, then 20
  47 //      };
  48
  49 //   print(letters.allMatches('The quick ! broWn').map((Match m) => m[0]).join());
  50
  51   String phr = "the traveller in the grey riding-coat, who called himself mr. melville, was "
  52                       "contemplating the malice of which the gods are capable.";
  53
  54 //  print(code1('the cat.'));
  55   print(code1(phr));
  56
  57 //  print(code2('the cat.'));
  58   print(code2(phr));
  59 }