Add crypto-square exercise (#120)

config.json

@@ -315,6 +315,16 @@
         "difficulty": 5,
         "topics": null
       },
+      {
+        "slug": "crypto-square",
+        "name": "Crypto Square",
+        "uuid": "6206d9b0-454e-4cf5-9c8e-dade7485e909",
+        "practices": [],
+        "prerequisites": [
+          "strings"
+        ],
+        "difficulty": 4
+      },
       {
         "slug": "complex-numbers",
         "name": "Complex Numbers",

exercises/practice/crypto-square/.docs/instructions.md

@@ -0,0 +1,71 @@
+# Instructions
+
+Implement the classic method for composing secret messages called a square code.
+
+Given an English text, output the encoded version of that text.
+
+First, the input is normalized: the spaces and punctuation are removed from the English text and the message is down-cased.
+
+Then, the normalized characters are broken into rows.
+These rows can be regarded as forming a rectangle when printed with intervening newlines.
+
+For example, the sentence
+
+```text
+"If man was meant to stay on the ground, god would have given us roots."
+```
+
+is normalized to:
+
+```text
+"ifmanwasmeanttostayonthegroundgodwouldhavegivenusroots"
+```
+
+The plaintext should be organized into a rectangle as square as possible.
+The size of the rectangle should be decided by the length of the message.
+
+If `c` is the number of columns and `r` is the number of rows, then for the rectangle `r` x `c` find the smallest possible integer `c` such that:
+
+- `r * c >= length of message`,
+- and `c >= r`,
+- and `c - r <= 1`.
+
+Our normalized text is 54 characters long, dictating a rectangle with `c = 8` and `r = 7`:
+
+```text
+"ifmanwas"
+"meanttos"
+"tayonthe"
+"groundgo"
+"dwouldha"
+"vegivenu"
+"sroots  "
+```
+
+The coded message is obtained by reading down the columns going left to right.
+
+The message above is coded as:
+
+```text
+"imtgdvsfearwermayoogoanouuiontnnlvtwttddesaohghnsseoau"
+```
+
+Output the encoded text in chunks that fill perfect rectangles `(r X c)`, with `c` chunks of `r` length, separated by spaces.
+For phrases that are `n` characters short of the perfect rectangle, pad each of the last `n` chunks with a single trailing space.
+
+```text
+"imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn  sseoau "
+```
+
+Notice that were we to stack these, we could visually decode the ciphertext back in to the original message:
+
+```text
+"imtgdvs"
+"fearwer"
+"mayoogo"
+"anouuio"
+"ntnnlvt"
+"wttddes"
+"aohghn "
+"sseoau "
+```

exercises/practice/crypto-square/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "ErikSchierboom"
+  ],
+  "files": {
+    "solution": [
+      "src/crypto_square.cljs"
+    ],
+    "test": [
+      "test/crypto_square_test.cljs"
+    ],
+    "example": [
+      ".meta/src/example.cljs"
+    ]
+  },
+  "blurb": "Implement the classic method for composing secret messages called a square code.",
+  "source": "J Dalbey's Programming Practice problems",
+  "source_url": "https://users.csc.calpoly.edu/~jdalbey/103/Projects/ProgrammingPractice.html"
+}

exercises/practice/crypto-square/.meta/src/example.cljs

@@ -0,0 +1,24 @@
+(ns crypto-square
+  (:require [clojure.string :as str]))
+
+(defn normalize-plaintext [plaintext]
+  (str/lower-case (str/replace plaintext #"[^\w]" "")))
+
+(defn square-size [plaintext]
+  (int (Math/ceil (Math/sqrt (count (normalize-plaintext plaintext))))))
+
+(defn plaintext-segments [plaintext]
+  (let [normalized-plaintext (normalize-plaintext plaintext)
+        size (square-size normalized-plaintext)]
+    (map #(apply str %) (partition size size nil normalized-plaintext))))
+
+(defn- padded-segments [plaintext pad]
+  (let [segments (plaintext-segments plaintext)
+        r (count (first segments))]
+        (map #(concat % (take (- r (count %)) (repeat pad))) segments)))
+
+(defn ciphertext [plaintext]
+  (apply str (apply mapcat vector (padded-segments plaintext nil))))
+
+(defn normalize-ciphertext [plaintext]
+  (str/join " " (map #(apply str %) (apply map vector (padded-segments plaintext \ )))))

exercises/practice/crypto-square/.meta/tests.toml

@@ -0,0 +1,24 @@
+# This is an auto-generated file. Regular comments will be removed when this
+# file is regenerated. Regenerating will not touch any manually added keys,
+# so comments can be added in a "comment" key.
+
+[407c3837-9aa7-4111-ab63-ec54b58e8e9f]
+description = "empty plaintext results in an empty ciphertext"
+
+[64131d65-6fd9-4f58-bdd8-4a2370fb481d]
+description = "Lowercase"
+
+[63a4b0ed-1e3c-41ea-a999-f6f26ba447d6]
+description = "Remove spaces"
+
+[1b5348a1-7893-44c1-8197-42d48d18756c]
+description = "Remove punctuation"
+
+[8574a1d3-4a08-4cec-a7c7-de93a164f41a]
+description = "9 character plaintext results in 3 chunks of 3 characters"
+
+[a65d3fa1-9e09-43f9-bcec-7a672aec3eae]
+description = "8 character plaintext results in 3 chunks, the last one with a trailing space"
+
+[fbcb0c6d-4c39-4a31-83f6-c473baa6af80]
+description = "54 character plaintext results in 7 chunks, the last two with trailing spaces"

exercises/practice/crypto-square/deps.edn

@@ -0,0 +1,10 @@
+{:deps
+ {org.clojure/clojure {:mvn/version "1.10.1"}
+  org.clojure/clojurescript {:mvn/version "1.10.773"}}
+
+ :aliases
+ {:test
+  {:extra-paths ["test"]
+   :extra-deps
+   {olical/cljs-test-runner {:mvn/version "3.8.0"}}
+   :main-opts ["-m" "cljs-test-runner.main"]}}}

exercises/practice/crypto-square/src/crypto_square.cljs

@@ -0,0 +1,21 @@
+(ns crypto-square)
+
+(defn normalize-plaintext [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn square-size [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn plaintext-segments [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn ciphertext [] ;; <- arglist goes here
+  ;; your code goes here
+)
+
+(defn normalize-ciphertext [] ;; <- arglist goes here
+  ;; your code goes here
+)

exercises/practice/crypto-square/test/crypto_square_test.cljs

@@ -0,0 +1,48 @@
+(ns crypto-square-test
+  (:require [clojure.test :refer [deftest is]]
+            crypto-square))
+
+(deftest normalize-splunk
+  (is (= "splunk" (crypto-square/normalize-plaintext "s#!@$%plunk"))))
+(deftest normalize-with-punctuation
+  (is (= "123go" (crypto-square/normalize-plaintext "1, 2, 3 GO!"))))
+
+(deftest square-2
+  (is (= 2 (crypto-square/square-size "1234"))))
+(deftest square-3
+  (is (= 3 (crypto-square/square-size "123456789"))))
+(deftest square-4
+  (is (= 4 (crypto-square/square-size "123456789abc"))))
+
+(deftest segments
+  (is (= ["neverv", "exthin", "eheart", "withid", "lewoes"]
+         (crypto-square/plaintext-segments "Never vex thine heart with idle woes."))))
+(deftest segments-2
+  (is (= ["zomg", "zomb", "ies"]
+         (crypto-square/plaintext-segments "ZOMG! ZOMBIES!!!"))))
+
+(deftest cipher-1
+  (is (= "tasneyinicdsmiohooelntuillibsuuml"
+         (crypto-square/ciphertext "Time is an illusion. Lunchtime doubly so."))))
+(deftest cipher-2
+  (is (= "wneiaweoreneawssciliprerlneoidktcms"
+         (crypto-square/ciphertext "We all know interspecies romance is weird."))))
+(deftest cipher-3
+  (is (= "vrel aepe mset paoo irpo"
+         (crypto-square/normalize-ciphertext "Vampires are people too!"))))
+(deftest cipher-4
+  (is (= "msemo aanin dnin  ndla  etlt  shui "
+         (crypto-square/normalize-ciphertext "Madness, and then illumination."))))
+(deftest cipher-5
+  (is (= (str "ageihdsednsh lsagtoonaepe lannswnccair hrditeaetnrh "
+              "ueethdnatoio mbqyewdnotto aouayicdwhod nranatosaef  "
+              "bnldrhnhrrb  efirersodir  irnieecusno  nedgnailoat ")
+         (let [plaintext (str "All human beings are born free "
+                              "and equal in dignity and rights. "
+                              "They are endowed with reason and conscience "
+                              "and should act towards one another "
+                              "in a spirit of brotherhood.")]
+           (crypto-square/normalize-ciphertext plaintext)))))
+(deftest cipher-6
+  (is (= "imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn  sseoau "
+         (crypto-square/normalize-ciphertext "If man was meant to stay on the ground, god would have given us roots."))))