- Added template for week 108.

1 files changed, 157 insertions, 0 deletions

diff --git a/challenge-108/abigail/README.md b/challenge-108/abigail/README.md
new file mode 100644
index 0000000000..67392c9e54
--- /dev/null
+++ b/challenge-108/abigail/README.md
@@ -0,0 +1,157 @@
+# Solution by Abigail
+## [Self-descriptive Numbers](https://perlweeklychallenge.org/blog/perl-weekly-challenge-107/#TASK1)
+
+Write a script to display the first three self-descriptive numbers.
+As per [wikipedia](https://en.wikipedia.org/wiki/Self-descriptive_number),
+the definition of Self-descriptive Number is
+
+> In mathematics, a self-descriptive number is an integer `m` that in a
+> given base `b` is `b` digits long in which each digit `d` at position `n`
+> (the most significant digit being at position 0 and the least
+> significant at position `b - 1`) counts how many instances of
+> digit `n` are in `m`.
+
+### Example
+~~~~
+ 1210 is a four-digit self-descriptive number:
+
+    position 0 has value 1 i.e. there is only one 0 in the number
+    position 1 has value 2 i.e. there are two 1 in the number
+    position 2 has value 1 i.e. there is only one 2 in the number
+    position 3 has value 0 i.e. there is no 3 in the number
+~~~~
+
+### Output
+~~~~
+    1210, 2020, 21200
+~~~~
+
+### Notes
+
+This is a trivial exercise -- as all exercises are which do not
+take any input, and which have a fixed output. Fixed output
+challenges are boring -- unless there's another condition (golf,
+for instance).
+
+This exercise is so trivial, we don't even have to head to the OEIS
+to download the wanted numbers, as the expected output is stated
+in the exercise.
+
+So, all we need to do is print three numbers, separated by commas.
+
+The easiest way would be to just do what the challenge demands
+from us, and print the output as given.
+
+A slightly less easy way would be to head over the given
+[Wikipedia page](https://en.wikipedia.org/wiki/Self-descriptive_number)
+(or the [OEIS](https://oeis.org) for that matter), copy the first
+three numbers, and print those out.
+
+But those solutions no doubt will cause scorn in two weeks,
+when the review comes out. It's all "advice about the code is the thing".
+
+But that raises the question, what is the code which is wanted? 
+You could generate all the numbers of length `b` in base `b`, while
+increasing `b`, test them for being self-descriptive, and print 
+the first three numbers found.
+
+My advice about brute force code when there is a more efficient way:
+Don't ever do that.
+
+If we just imagine the Wikipedia page didn't list any self-descriptive
+numbers, and Neil Sloane has forgotten to pay the fee for the OEIS
+domain, so it was taken off-line, then it's still easy to determine
+the first three self-descriptive numbers -- no code required.
+
+Given the following observations for a self-descriptive number `N` in base `b`:
+* `N` has `b` digits, and does not start with a `0`.
+* The sum of the digits of `N` is `b`.
+* No digit of `N` equals `b - 1`.
+* The last digit of `N` is `0`.
+* If `b > 4`, then `N` does not start with a `1`.
+* If `b > 4`, then `N` does not start with `b - 2`.
+
+From that, it's easy to determine that:
+* There are no self-descriptive numbers in any base below `4`.
+* A self-descriptive number in base `4` must start with a `1` or `2`. And
+  end with a `0`. If it starts with a `1`, the middle digits are `1` and `2`.
+  If it starts with a `2`, the middle digits are `0` and `2`. Both `1210`,
+  and `2020"`are self-descriptive numbers.
+* A self-descriptive number in base `5` must start with a `2`, and end
+  with a `0`. The three middle digits must be `0`, `1`, and `2`. `21200`
+  is a self-descriptive number.
+
+(For a more detailed derivation, with all the details filled in, see [the blog
+post](https://abigail.github.io/HTML/Perl-Weekly-Challenge/week-107-1.html))
+
+But this still makes this challenge a glorified `Hello, World!`
+program, as there is no useful code to write to generate the numbers.
+
+### Solutions
+* [AWK](awk/ch-1.awk)
+* [Bash](bash/ch-1.awk)
+* [BASIC](basic/ch-1.bas)
+* [bc](bc/ch-1.bc)
+* [Befunge-93](befunge-93/ch-1.bf93)
+* [C](c/ch-1.c)
+* [Cobol](cobol/ch-1.cb)
+* [Csh](csh/ch-1.csh)
+* [Erlang](erlang/ch-1.erl)
+* [Forth](forth/ch-1.fs)
+* [Fortran](fortran/ch-1.fs)
+* [Go](go/ch-1.go)
+* [Java](java/ch-1.java)
+* [Lua](lua/ch-1.lua)
+* [m4](m4/ch-1.m4)
+* [Node.js](lua/ch-1.js)
+* [OCaml](ocaml/ch-1.ml)
+* [Pascal](pascal/ch-1.pl)
+* [Perl](perl/ch-1.pl)
+* [PHP](php/ch-1.pl)
+* [PostScript](postscript/ch-1.ps)
+* [Python](python/ch-1.py)
+* [R](r/ch-1.r)
+* [Rexx](rexx/ch-1.rexx)
+* [Ruby](ruby/ch-1.rb)
+* [Scheme](scheme/ch-1.scm)
+* [sed](sed/ch-1.sed)
+* [SQL](sql/ch-1.sql)
+* [Tcl](tcl/ch-1.tcl)
+
+### Blog
+[Perl Weekly Challenge 107: Self-descriptive Numbers](https://abigail.github.io/HTML/Perl-Weekly-Challenge/week-107-1.html)
+
+## [List Methods](https://perlweeklychallenge.org/blog/perl-weekly-challenge-107/#TASK2)
+
+Write a script to list methods of a package/class.
+
+### Example
+Given the package:
+~~~~
+package Calc;
+
+use strict;
+use warnings;
+
+sub new { bless {}, shift; }
+sub add { }
+sub mul { }
+sub div { }
+
+1;
+~~~~
+Output:
+~~~~
+BEGIN
+mul
+div
+new
+add
+~~~~
+
+### Solutions
+* [Perl](perl/ch-2.pl)
+
+### Blog
+[Perl Weekly Challenge 107: List Methods](https://abigail.github.io/HTML/Perl-Weekly-Challenge/week-107-2.html)
+