Add isogram exercise (#366)

config.json

@@ -195,6 +195,18 @@
           "strings"
         ]
       },
+      {
+        "slug": "isogram",
+        "name": "Isogram",
+        "uuid": "63fc7e59-2448-487b-9b66-06c72ab8d6b0",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2,
+        "topics": [
+          "control_flow_loops",
+          "strings"
+        ]
+      },
       {
         "slug": "leap",
         "name": "Leap",

exercises/practice/isogram/.docs/instructions.md

@@ -0,0 +1,14 @@
+# Instructions
+
+Determine if a word or phrase is an isogram.
+
+An isogram (also known as a "non-pattern word") is a word or phrase without a repeating letter, however spaces and hyphens are allowed to appear multiple times.
+
+Examples of isograms:
+
+- lumberjacks
+- background
+- downstream
+- six-year-old
+
+The word _isograms_, however, is not an isogram, because the s repeats.

exercises/practice/isogram/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "isogram.el"
+    ],
+    "test": [
+      "isogram-test.el"
+    ],
+    "example": [
+      ".meta/example.el"
+    ]
+  },
+  "blurb": "Determine if a word or phrase is an isogram.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Isogram"
+}

exercises/practice/isogram/.meta/example.el

@@ -0,0 +1,27 @@
+;;; isogram.el --- isogram (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'cl-lib)
+
+(defun upper-char-p (c)
+  "Determine if char C is alphabetic and upper case."
+  (and
+   (>= c ?A)
+   (<= c ?Z)))
+
+(defun isogramp (phrase)
+  "Determine if a given phrase is an isogram."
+  (let* ((bitset 0)
+         (updated 0)
+         (characters (cl-coerce (upcase phrase) 'list))
+         (letters (cl-remove-if-not 'upper-char-p characters)))
+    (cl-loop for c in letters
+      do (setq updated (logior bitset (lsh 1 (- c ?A))))
+      always (> updated bitset)
+      do (setq bitset updated))))
+
+(provide 'isogram)
+;;; isogram.el ends here

exercises/practice/isogram/.meta/tests.toml

@@ -0,0 +1,52 @@
+# 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.
+
+[a0e97d2d-669e-47c7-8134-518a1e2c4555]
+description = "empty string"
+
+[9a001b50-f194-4143-bc29-2af5ec1ef652]
+description = "isogram with only lower case characters"
+
+[8ddb0ca3-276e-4f8b-89da-d95d5bae78a4]
+description = "word with one duplicated character"
+
+[6450b333-cbc2-4b24-a723-0b459b34fe18]
+description = "word with one duplicated character from the end of the alphabet"
+
+[a15ff557-dd04-4764-99e7-02cc1a385863]
+description = "longest reported english isogram"
+
+[f1a7f6c7-a42f-4915-91d7-35b2ea11c92e]
+description = "word with duplicated character in mixed case"
+
+[14a4f3c1-3b47-4695-b645-53d328298942]
+description = "word with duplicated character in mixed case, lowercase first"
+
+[423b850c-7090-4a8a-b057-97f1cadd7c42]
+description = "hypothetical isogrammic word with hyphen"
+
+[93dbeaa0-3c5a-45c2-8b25-428b8eacd4f2]
+description = "hypothetical word with duplicated character following hyphen"
+
+[36b30e5c-173f-49c6-a515-93a3e825553f]
+description = "isogram with duplicated hyphen"
+
+[cdabafa0-c9f4-4c1f-b142-689c6ee17d93]
+description = "made-up name that is an isogram"
+
+[5fc61048-d74e-48fd-bc34-abfc21552d4d]
+description = "duplicated character in the middle"
+
+[310ac53d-8932-47bc-bbb4-b2b94f25a83e]
+description = "same first and last characters"
+
+[0d0b8644-0a1e-4a31-a432-2b3ee270d847]
+description = "word with duplicated character and with two hyphens"

exercises/practice/isogram/isogram-test.el

@@ -0,0 +1,68 @@
+;;; isogram-test.el --- Tests for Isogram (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+(load-file "isogram.el")
+(declare-function isogramp "isogram.el" (phrase))
+
+
+(ert-deftest empty-string ()
+  (should (isogramp "")))
+
+
+(ert-deftest isogram-with-only-lower-case-characters ()
+  (should (isogramp "isogram")))
+
+
+(ert-deftest word-with-one-duplicated-character ()
+  (should-not (isogramp "eleven")))
+
+
+(ert-deftest word-with-one-duplicated-character-from-the-end-of-the-alphabet ()
+  (should-not (isogramp "zzyzx")))
+
+
+(ert-deftest longest-reported-english-isogram ()
+  (should (isogramp "subdermatoglyphic")))
+
+
+(ert-deftest word-with-duplicated-character-in-mixed-case ()
+  (should-not (isogramp "Alphabet")))
+
+
+(ert-deftest word-with-duplicated-character-in-mixed-case-lowercase-first ()
+  (should-not (isogramp "alphAbet")))
+
+
+(ert-deftest hypothetical-isogrammic-word-with-hyphen ()
+  (should (isogramp "thumbscrew-japingly")))
+
+
+(ert-deftest hypothetical-word-with-duplicated-character-following-hyphen ()
+  (should-not (isogramp "thumbscrew-jappingly")))
+
+
+(ert-deftest isogram-with-duplicated-hyphen ()
+  (should (isogramp "six-year-old")))
+
+
+(ert-deftest made-up-name-that-is-an-isogram ()
+  (should (isogramp "Emily Jung Schwartzkopf")))
+
+
+(ert-deftest duplicated-character-in-the-middle ()
+  (should-not (isogramp "accentor")))
+
+
+(ert-deftest same-first-and-last-characters ()
+  (should-not (isogramp "angola")))
+
+
+(ert-deftest word-with-duplicated-character-and-with-two-hyphens ()
+  (should-not (isogramp "up-to-date")))
+
+
+(provide 'isogram-test)
+;;; isogram-test.el ends here

exercises/practice/isogram/isogram.el

@@ -0,0 +1,13 @@
+;;; isogram.el --- isogram (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+
+(defun isogramp (phrase)
+  (error "Delete this S-Expression and write your own implementation"))
+
+
+(provide 'isogram)
+;;; isogram.el ends here