Add armstrong-numbers exercise

config.json

@@ -178,6 +178,14 @@
         ],
         "difficulty": 1
       },
+      {
+        "slug": "armstrong-numbers",
+        "name": "Armstrong Numbers",
+        "uuid": "bbc8720e-597c-4ae9-b39b-2f0fb8e6578d",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "atbash-cipher",
         "name": "Atbash Cipher",

exercises/practice/armstrong-numbers/.docs/instructions.md

@@ -0,0 +1,14 @@
+# Instructions
+
+An [Armstrong number][armstrong-number] is a number that is the sum of its own digits each raised to the power of the number of digits.
+
+For example:
+
+- 9 is an Armstrong number, because `9 = 9^1 = 9`
+- 10 is _not_ an Armstrong number, because `10 != 1^2 + 0^2 = 1`
+- 153 is an Armstrong number, because: `153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153`
+- 154 is _not_ an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`
+
+Write some code to determine whether a number is an Armstrong number.
+
+[armstrong-number]: https://en.wikipedia.org/wiki/Narcissistic_number

exercises/practice/armstrong-numbers/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "glennj"
+  ],
+  "files": {
+    "solution": [
+      "lib/ArmstrongNumbers.pm"
+    ],
+    "test": [
+      "t/armstrong-numbers.t"
+    ],
+    "example": [
+      ".meta/solutions/lib/ArmstrongNumbers.pm"
+    ]
+  },
+  "blurb": "Determine if a number is an Armstrong number.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Narcissistic_number"
+}

exercises/practice/armstrong-numbers/.meta/solutions/lib/ArmstrongNumbers.pm

@@ -0,0 +1,24 @@
+package ArmstrongNumbers;
+
+use strict;
+use warnings;
+use experimental qw<signatures postderef postderef_qq>;
+
+use Exporter qw<import>;
+our @EXPORT_OK = qw<is_armstrong_number>;
+
+use bignum;
+
+sub is_armstrong_number ($number) {
+    my $n    = $number->copy();
+    my $size = $n->length();
+    my $sum  = Math::BigInt->bzero();
+    my $rem;
+    while ( $n->is_positive() ) {
+        ( $n, $rem ) = $n->bdiv(10);
+        $sum = $sum->badd( $rem->bpow($size) );
+    }
+    return $sum->beq($number);
+}
+
+1;

exercises/practice/armstrong-numbers/.meta/solutions/t/armstrong-numbers.t

@@ -0,0 +1 @@
+../../../t/armstrong-numbers.t

exercises/practice/armstrong-numbers/.meta/template-data.yaml

@@ -0,0 +1,34 @@
+subs: is_armstrong_number
+modules: 
+  - use: bignum;
+properties:
+  isArmstrongNumber:
+    test: |-
+      use Data::Dmp;
+      sprintf(<<'END', $case->{input}{number}, $case->{expected} ? ('T', '# True') : ('DF', '# Defined but False'), dmp($case->{description}));
+      is(
+          is_armstrong_number(%s),
+          %s, %s
+          %s
+      );
+      END
+
+stub: |-
+  sub is_armstrong_number ($number) {
+      return undef;
+  }
+
+example: |-
+  use bignum;
+
+  sub is_armstrong_number ($number) {
+      my $n = $number->copy();
+      my $size = $n->length();
+      my $sum = Math::BigInt->bzero();
+      my $rem;
+      while ($n->is_positive()) {
+          ($n, $rem) = $n->bdiv(10);
+          $sum = $sum->badd($rem->bpow($size));
+      }
+      return $sum->beq($number);
+  }

exercises/practice/armstrong-numbers/.meta/tests.toml

@@ -0,0 +1,43 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[c1ed103c-258d-45b2-be73-d8c6d9580c7b]
+description = "Zero is an Armstrong number"
+
+[579e8f03-9659-4b85-a1a2-d64350f6b17a]
+description = "Single-digit numbers are Armstrong numbers"
+
+[2d6db9dc-5bf8-4976-a90b-b2c2b9feba60]
+description = "There are no two-digit Armstrong numbers"
+
+[509c087f-e327-4113-a7d2-26a4e9d18283]
+description = "Three-digit number that is an Armstrong number"
+
+[7154547d-c2ce-468d-b214-4cb953b870cf]
+description = "Three-digit number that is not an Armstrong number"
+
+[6bac5b7b-42e9-4ecb-a8b0-4832229aa103]
+description = "Four-digit number that is an Armstrong number"
+
+[eed4b331-af80-45b5-a80b-19c9ea444b2e]
+description = "Four-digit number that is not an Armstrong number"
+
+[f971ced7-8d68-4758-aea1-d4194900b864]
+description = "Seven-digit number that is an Armstrong number"
+
+[7ee45d52-5d35-4fbd-b6f1-5c8cd8a67f18]
+description = "Seven-digit number that is not an Armstrong number"
+
+[5ee2fdf8-334e-4a46-bb8d-e5c19c02c148]
+description = "Armstrong number containing seven zeroes"
+
+[12ffbf10-307a-434e-b4ad-c925680e1dd4]
+description = "The largest and last Armstrong number"

exercises/practice/armstrong-numbers/lib/ArmstrongNumbers.pm

@@ -0,0 +1,12 @@
+package ArmstrongNumbers;
+
+use v5.40;
+
+use Exporter qw<import>;
+our @EXPORT_OK = qw<is_armstrong_number>;
+
+sub is_armstrong_number ($number) {
+    return undef;
+}
+
+1;

exercises/practice/armstrong-numbers/t/armstrong-numbers.t

@@ -0,0 +1,76 @@
+#!/usr/bin/env perl
+use Test2::V0;
+
+use FindBin qw<$Bin>;
+use lib "$Bin/../lib", "$Bin/../local/lib/perl5";
+
+use ArmstrongNumbers qw<is_armstrong_number>;
+use bignum;
+
+is( # begin: c1ed103c-258d-45b2-be73-d8c6d9580c7b
+    is_armstrong_number(0),
+    T, # True
+    "Zero is an Armstrong number"
+); # end: c1ed103c-258d-45b2-be73-d8c6d9580c7b
+
+is( # begin: 579e8f03-9659-4b85-a1a2-d64350f6b17a
+    is_armstrong_number(5),
+    T, # True
+    "Single-digit numbers are Armstrong numbers"
+); # end: 579e8f03-9659-4b85-a1a2-d64350f6b17a
+
+is( # begin: 2d6db9dc-5bf8-4976-a90b-b2c2b9feba60
+    is_armstrong_number(10),
+    DF, # Defined but False
+    "There are no two-digit Armstrong numbers"
+); # end: 2d6db9dc-5bf8-4976-a90b-b2c2b9feba60
+
+is( # begin: 509c087f-e327-4113-a7d2-26a4e9d18283
+    is_armstrong_number(153),
+    T, # True
+    "Three-digit number that is an Armstrong number"
+); # end: 509c087f-e327-4113-a7d2-26a4e9d18283
+
+is( # begin: 7154547d-c2ce-468d-b214-4cb953b870cf
+    is_armstrong_number(100),
+    DF, # Defined but False
+    "Three-digit number that is not an Armstrong number"
+); # end: 7154547d-c2ce-468d-b214-4cb953b870cf
+
+is( # begin: 6bac5b7b-42e9-4ecb-a8b0-4832229aa103
+    is_armstrong_number(9474),
+    T, # True
+    "Four-digit number that is an Armstrong number"
+); # end: 6bac5b7b-42e9-4ecb-a8b0-4832229aa103
+
+is( # begin: eed4b331-af80-45b5-a80b-19c9ea444b2e
+    is_armstrong_number(9475),
+    DF, # Defined but False
+    "Four-digit number that is not an Armstrong number"
+); # end: eed4b331-af80-45b5-a80b-19c9ea444b2e
+
+is( # begin: f971ced7-8d68-4758-aea1-d4194900b864
+    is_armstrong_number(9926315),
+    T, # True
+    "Seven-digit number that is an Armstrong number"
+); # end: f971ced7-8d68-4758-aea1-d4194900b864
+
+is( # begin: 7ee45d52-5d35-4fbd-b6f1-5c8cd8a67f18
+    is_armstrong_number(9926314),
+    DF, # Defined but False
+    "Seven-digit number that is not an Armstrong number"
+); # end: 7ee45d52-5d35-4fbd-b6f1-5c8cd8a67f18
+
+is( # begin: 5ee2fdf8-334e-4a46-bb8d-e5c19c02c148
+    is_armstrong_number(186709961001538790100634132976990),
+    T, # True
+    "Armstrong number containing seven zeroes"
+); # end: 5ee2fdf8-334e-4a46-bb8d-e5c19c02c148
+
+is( # begin: 12ffbf10-307a-434e-b4ad-c925680e1dd4
+    is_armstrong_number(115132219018763992565095597973971522401),
+    T, # True
+    "The largest and last Armstrong number"
+); # end: 12ffbf10-307a-434e-b4ad-c925680e1dd4
+
+done_testing;