Add challenge-135

1 files changed, 29 insertions, 18 deletions

diff --git a/challenge-135/andinus/README b/challenge-135/andinus/README
index 1d5171cfa8..bd1dd6e3ce 100644
--- a/challenge-135/andinus/README
+++ b/challenge-135/andinus/README
@@ -1,40 +1,51 @@
                             ━━━━━━━━━━━━━━━
-                             CHALLENGE 134
+                             CHALLENGE 135
 
                                 Andinus
                             ━━━━━━━━━━━━━━━
 
 
-                               2021-10-11
+                               2021-10-22
 
 
 
 
 
-Task 1 - Pandigital Numbers
-═══════════════════════════
+Task 1 - Middle 3-digits
+════════════════════════
 
-  Write a script to generate first 5 Pandigital Numbers in base 10.
+  You are given an integer.
 
-  As per the [wikipedia], it says:
-
-        A pandigital number is an integer that in a given base has
-        among its significant digits each digit used in the base
-        at least once.
+  Write a script find out the middle 3-digits of the given integer, if
+  possible otherwise throw sensible error.
 
+  ┌────
+  │ Input: $n = 1234567
+  │ Output: 345
+  │
+  │ Input: $n = -123
+  │ Output: 123
+  │
+  │ Input: $n = 1
+  │ Output: too short
+  │
+  │ Input: $n = 10
+  │ Output: even number of digits
+  └────
 
-[wikipedia] <https://en.wikipedia.org/wiki/Pandigital_number>
 
 Raku
 ────
 
-  • Program: <file:raku/ch-1.raku>
-
-  Loop from 1023456789 (first Pandigital Number) and take if it contains
-  every digit in base 10.
+  Input's absolute value is taken because the sign is meaningless here.
+  To get middle 3-digits we take 3 digits from `$n.chars div 2 - 1'
+  position, `-1' because Arrays are 0-indexed. It's guaranteed that we
+  have odd number of digits so `div 2' will land us on left of middle
+  digit, we just take 3 digits from there.
 
   ┌────
-  │ put gather for 1023456789 .. ∞ {
-  │     .take if .comb>>.Int.Set ≡ (0 .. 9).Set;
-  │ }[^5]
+  │ $n = abs $n;
+  │ die "too short" if $n.chars < 3;
+  │ die "even number of digits" if $n.chars %% 2;
+  │ put $n.substr($n.chars div 2 - 1, 3);
   └────