Challenge 261 Solutions (Raku)

3 files changed, 21 insertions, 132 deletions

diff --git a/challenge-261/mark-anderson/blog-2.md b/challenge-261/mark-anderson/blog-2.md
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-# Weekly Challenge #260
-
-### Task 2: Dictionary Rank
-**Submitted by: Mark Anderson**
-
-You are given a word, ```$word```.
-
-Write a script to compute the dictionary rank of the given word.
-
-#### Example 1
-```
-Input: $word = 'CAT'
-Output: 3
-
-All possible combinations of the letters:
-CAT, CTA, ATC, TCA, ACT, TAC
-
-Arrange them in alphabetical order:
-ACT, ATC, CAT, CTA, TAC, TCA
-
-CAT is the 3rd in the list.
-Therefore the dictionary rank of CAT is 3.
-```
-
-#### Example 2
-```
-Input: $word = 'GOOGLE'
-Output: 88
-```
-
-#### Example 3
-```
-Input: $word = 'SECRET'
-Output: 255
-```
-
----
-
-### Solution
-
-One approach is to create all permutations, sort them, and find the index of ```$word```.
-
-This is fine for short words but there's a better solution for long words.
-
-There are numerous videos on youtube explaining the algorithm - I think this a good one [https://www.youtube.com/watch?v=-MpL0X3AHAs](https://www.youtube.com/watch?v=-MpL0X3AHAs)
-
-Here's the gist of the algorithm:
-
-1. Find the rank of each letter.
-
-   ```
-   G O O G L E
-   1 3 3 1 2 0
-   ```
-
-2. For each letter, find the number of letters to its right that have a lower rank.
-
-   ```
-   G O O G L E
-   1 3 3 1 1 0
-   ```
-
-3. For each letter, take the number of repeating letters from that letter to the end of the string.
-   Take the factorial of each result and multiply them together.
-   
-   ```  
-     G    O   O  G  L  E
-   2!*2!  2!  1! 1! 1! 1!
-   ```
-
-   Starting with the first letter, there are 2 Gs and 2 Os so we end up with 2!*2!.
-   The next letter is O. From that letter to the end of the string there is just the repeating O so we end up with 2!
-   and so on.
-   
-4. Take the terms from step 2 and divide them by the terms from step 3.
- 
-   ```
-    G    O    O   G   L    E
-   1/4  3/2  3/1 1/1 1/1  0/1
-   ```
-
-5. Create the sequence ```$word```.end...0 and take the factorial of each term.
-
-   ```
-   G  O  O  G  L  E
-   5! 4! 3! 2! 1! 0!
-   ```
-   
-6. Multipy the terms from step 4 with the terms from step 5.
-
-   ```
-     G       O       O     G    L    E
-   120/4  (3*24)/2  3*6   1*2  1*1  0*1
-   ```
-   
-7. Sum the terms from step 6 and add 1 for a result of 88.
-   ```
-   G    O    O    G   L   E
-   30 + 36 + 18 + 2 + 1 + 0 + 1 = 88
-   ```
-### My translation to Raku:
-
-```
-#!/usr/bin/env raku
-use experimental :cached;
-
-say rank('google');
-
-sub postfix:<!>($n) is cached { [*] 1..$n }
-
-sub rank($word)
-{
-    my @w = $word.comb;
-    my @ranks = @w.sort.squish.antipairs.Map{@w}; 
-    my $bag = @ranks.BagHash;
-
-    my @n = gather for @ranks -> $r
-    {
-        my @less-than = $bag.keys.grep(* < $r);
-        take ([+] $bag{@less-than}) / ([*] $bag.values>>!);
-        $bag{$r}--
-    }
-        
-    1 + [+] @n Z* (@ranks.end...0)>>!
-}
-```
-
-[The full program.](https://github.com/manwar/perlweeklychallenge-club/blob/master/challenge-260/mark-anderson/raku/ch-2.raku)
-
-Thank you for reading my solution to the [Weekly Challenge #260 Task #2.](https://theweeklychallenge.org/blog/perl-weekly-challenge-260/)
-
-*-Mark Anderson*
diff --git a/challenge-261/mark-anderson/raku/ch-1.raku b/challenge-261/mark-anderson/raku/ch-1.raku
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+#!/usr/bin/env raku
+use Test;
+
+is element-digit-sum(1,2,3,45),             36;
+is element-digit-sum(1,12,3),                9;
+is element-digit-sum(1,2,3,4),               0;
+is element-digit-sum(236,416,336,350),    1296;
+
+sub element-digit-sum(+@ints)
+{
+    abs ([+] @ints) - [+] @ints.comb(/<digit>/)
+}
diff --git a/challenge-261/mark-anderson/raku/ch-2.raku b/challenge-261/mark-anderson/raku/ch-2.raku
new file mode 100644
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@@ -0,0 +1,9 @@
+#!/usr/bin/env raku
+use Test;
+
+is multiply-by-two([5,3,6,1,12], 3), 24;
+is multiply-by-two([1,2,4,3], 1),     8;
+is multiply-by-two([5,6,7], 2),       2;
+
+multi multiply-by-two(@i, $s)                    { return $s            }
+multi multiply-by-two(@i, $s where $s (elem) @i) { samewith(@i, $s * 2) }