Add parallel-letter-frequency

config.json

@@ -894,6 +894,14 @@
         "prerequisites": [],
         "difficulty": 8
       },
+      {
+        "slug": "parallel-letter-frequency",
+        "name": "Parallel Letter Frequency",
+        "uuid": "5b856b54-c8be-4d90-be7c-60a441625fd0",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 8
+      },
       {
         "slug": "minesweeper",
         "name": "Minesweeper",

exercises/practice/parallel-letter-frequency/.docs/instructions.md

@@ -0,0 +1,7 @@
+# Instructions
+
+Count the frequency of letters in texts using parallel computation.
+
+Parallelism is about doing things in parallel that can also be done sequentially.
+A common example is counting the frequency of letters.
+Employ parallelism to calculate the total frequency of each letter in a list of texts.

exercises/practice/parallel-letter-frequency/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": [
+    "BNAndras",
+    "CoolKatt"
+  ],
+  "files": {
+    "solution": [
+      "parallel-letter-frequency.coffee"
+    ],
+    "test": [
+      "parallel-letter-frequency.spec.coffee"
+    ],
+    "example": [
+      ".meta/example.coffee"
+    ]
+  },
+  "blurb": "Count the frequency of letters in texts using parallel computation."
+}

exercises/practice/parallel-letter-frequency/.meta/example.coffee

@@ -0,0 +1,33 @@
+{ Worker } = require 'node:worker_threads'
+
+class ParallelLetterFrequency
+  @parallelLetterFrequency: (texts) ->
+    formatedTexts = texts
+      .map (x) ->
+        x.toLowerCase().match(/\p{Letter}+/gu)?.join('') ? ''
+      .filter (x) -> x isnt ''
+
+    processSingleText = (text) ->
+      new Promise (resolve, reject) ->
+        workerCode = """
+          const { workerData, parentPort } = require('node:worker_threads');
+          const countInWorker = (data) =>
+            [...data].reduce((acc, cur) => {
+              acc[cur] = (acc[cur] || 0) + 1;
+              return acc;
+            }, {});
+          parentPort.postMessage(countInWorker(workerData));
+        """
+        worker = new Worker workerCode, eval: true, workerData: text
+        worker.on 'message', resolve
+        worker.on 'error', reject
+
+    Promise.all formatedTexts.map(processSingleText)
+      .then (results) ->
+        results.reduce (acc, cur) ->
+          for letter, count of cur
+            acc[letter] = (acc[letter] or 0) + count
+          acc
+        , {}
+
+module.exports = ParallelLetterFrequency

exercises/practice/parallel-letter-frequency/.meta/tests.toml

@@ -0,0 +1,49 @@
+# 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.
+
+[c054d642-c1fa-4234-8007-9339f2337886]
+description = "no texts"
+
+[818031be-49dc-4675-b2f9-c4047f638a2a]
+description = "one text with one letter"
+
+[c0b81d1b-940d-4cea-9f49-8445c69c17ae]
+description = "one text with multiple letters"
+
+[708ff1e0-f14a-43fd-adb5-e76750dcf108]
+description = "two texts with one letter"
+
+[1b5c28bb-4619-4c9d-8db9-a4bb9c3bdca0]
+description = "two texts with multiple letters"
+
+[6366e2b8-b84c-4334-a047-03a00a656d63]
+description = "ignore letter casing"
+
+[92ebcbb0-9181-4421-a784-f6f5aa79f75b]
+description = "ignore whitespace"
+
+[bc5f4203-00ce-4acc-a5fa-f7b865376fd9]
+description = "ignore punctuation"
+
+[68032b8b-346b-4389-a380-e397618f6831]
+description = "ignore numbers"
+
+[aa9f97ac-3961-4af1-88e7-6efed1bfddfd]
+description = "Unicode letters"
+
+[7b1da046-701b-41fc-813e-dcfb5ee51813]
+description = "combination of lower- and uppercase letters, punctuation and white space"
+
+[4727f020-df62-4dcf-99b2-a6e58319cb4f]
+description = "large texts"
+
+[adf8e57b-8e54-4483-b6b8-8b32c115884c]
+description = "many small texts"

exercises/practice/parallel-letter-frequency/parallel-letter-frequency.coffee

@@ -0,0 +1,4 @@
+class ParallelLetterFrequency
+  @parallelLetterFrequency: (texts) ->
+
+module.exports = ParallelLetterFrequency