Add armstrong-numbers exercise

config.json

@@ -99,6 +99,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 2
+      },
+      {
+        "slug": "armstrong-numbers",
+        "name": "Armstrong Numbers",
+        "uuid": "9f87d2dd-b46c-437e-8a69-7f3ed44af244",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
       }
     ]
   },

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": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "src/armstrong-numbers.art"
+    ],
+    "test": [
+      "tests/test-armstrong-numbers.art"
+    ],
+    "example": [
+      ".meta/src/example.art"
+    ]
+  },
+  "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/src/example.art

@@ -0,0 +1,7 @@
+armstrong_sum: $ [n][
+    digits_: digits n
+    numDigits_: size digits_
+    sum map digits_ => [& ^ numDigits_]
+]
+
+armstrong?: $ [n][n = armstrong_sum n]

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/src/armstrong-numbers.art

@@ -0,0 +1,3 @@
+armstrong?: function[n][
+    panic "Please implement the armstrong? function"
+]

exercises/practice/armstrong-numbers/tester.art

@@ -0,0 +1,3 @@
+import {unitt}!
+
+runTests.failFast findTests "tests"

exercises/practice/armstrong-numbers/tests/test-armstrong-numbers.art

@@ -0,0 +1,59 @@
+import {unitt}!
+import {src/armstrong-numbers}!
+
+suite "Armstrong Numbers" [
+    test "Zero is an Armstrong number" [
+        result: armstrong? 0
+        assert -> true = result
+    ]
+
+    test.skip "Single digit numbers are Armstrong numbers" [
+        result: armstrong? 5
+        assert -> true = result
+    ]
+
+    test.skip "There are no 2 digit Armstrong Numbers" [
+        result: armstrong? 10
+        assert -> false = result
+    ]
+
+    test.skip "Three digit number that is not an Armstrong number" [
+        result: armstrong? 100
+        assert -> false = result
+    ]
+
+    test.skip "Three digit number that is an Armstrong number" [
+        result: armstrong? 153
+        assert -> true = result
+    ]
+
+    test.skip "Four digit number that is an Armstrong number" [
+        result: armstrong? 9474
+        assert -> true = result
+    ]
+
+    test.skip "Four digit number that is not an Armstrong number" [
+        result: armstrong? 9475
+        assert -> false = result
+    ]
+
+    test.skip "Seven digit number that is not an Armstrong number" [
+        result: armstrong? 9926314
+        assert -> false = result
+    ]
+
+    test.skip "Seven digit number that is an Armstrong number" [
+        result: armstrong? 9926315
+        assert -> true = result
+    ]
+
+    test.skip "Armstrong number containing seven zeroes" [
+        result: armstrong? 186709961001538790100634132976990
+        assert -> true = result
+    ]
+
+    test.skip "The largest and last Armstrong number" [
+        result: armstrong? 115132219018763992565095597973971522401
+        assert -> true = result
+    ]
+]