Add ocr-numbers exercise (#271)

Author: keiravillekode

config.json

@@ -728,6 +728,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "ocr-numbers",
+        "name": "OCR Numbers",
+        "uuid": "5890a278-557d-443f-8bbf-8abed66b185e",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "parallel-letter-frequency",
         "name": "Parallel Letter Frequency",

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

@@ -0,0 +1,79 @@
+# Instructions
+
+Given a 3 x 4 grid of pipes, underscores, and spaces, determine which number is represented, or whether it is garbled.
+
+## Step One
+
+To begin with, convert a simple binary font to a string containing 0 or 1.
+
+The binary font uses pipes and underscores, four rows high and three columns wide.
+
+```text
+     _   #
+    | |  # zero.
+    |_|  #
+         # the fourth row is always blank
+```
+
+Is converted to "0"
+
+```text
+         #
+      |  # one.
+      |  #
+         # (blank fourth row)
+```
+
+Is converted to "1"
+
+If the input is the correct size, but not recognizable, your program should return '?'
+
+If the input is the incorrect size, your program should return an error.
+
+## Step Two
+
+Update your program to recognize multi-character binary strings, replacing garbled numbers with ?
+
+## Step Three
+
+Update your program to recognize all numbers 0 through 9, both individually and as part of a larger string.
+
+```text
+ _
+ _|
+|_
+
+```
+
+Is converted to "2"
+
+```text
+      _  _     _  _  _  _  _  _  #
+    | _| _||_||_ |_   ||_||_|| | # decimal numbers.
+    ||_  _|  | _||_|  ||_| _||_| #
+                                 # fourth line is always blank
+```
+
+Is converted to "1234567890"
+
+## Step Four
+
+Update your program to handle multiple numbers, one per line.
+When converting several lines, join the lines with commas.
+
+```text
+    _  _
+  | _| _|
+  ||_  _|
+
+    _  _
+|_||_ |_
+  | _||_|
+
+ _  _  _
+  ||_||_|
+  ||_| _|
+
+```
+
+Is converted to "123,456,789".

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

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "ocr-numbers.v"
+    ],
+    "test": [
+      "run_test.v"
+    ],
+    "example": [
+      ".meta/example.v"
+    ]
+  },
+  "blurb": "Given a 3 x 4 grid of pipes, underscores, and spaces, determine which number is represented, or whether it is garbled.",
+  "source": "Inspired by the Bank OCR kata",
+  "source_url": "https://codingdojo.org/kata/BankOCR/"
+}

exercises/practice/ocr-numbers/.meta/example.v

@@ -0,0 +1,59 @@
+module main
+
+import strings
+
+fn convert_digit(first string, second string, third string, fourth string) rune {
+	return if fourth != '   ' {
+		`?`
+	} else if first == ' _ ' && second == '| |' && third == '|_|' {
+		`0`
+	} else if first == '   ' && second == '  |' && third == '  |' {
+		`1`
+	} else if first == ' _ ' && second == ' _|' && third == '|_ ' {
+		`2`
+	} else if first == ' _ ' && second == ' _|' && third == ' _|' {
+		`3`
+	} else if first == '   ' && second == '|_|' && third == '  |' {
+		`4`
+	} else if first == ' _ ' && second == '|_ ' && third == ' _|' {
+		`5`
+	} else if first == ' _ ' && second == '|_ ' && third == '|_|' {
+		`6`
+	} else if first == ' _ ' && second == '  |' && third == '  |' {
+		`7`
+	} else if first == ' _ ' && second == '|_|' && third == '|_|' {
+		`8`
+	} else if first == ' _ ' && second == '|_|' && third == ' _|' {
+		`9`
+	} else {
+		`?`
+	}
+}
+
+fn convert(rows []string) !string {
+	if rows.len % 4 != 0 {
+		return error('Number of input lines is not a multiple of four')
+	}
+	if rows[0].len % 3 != 0 {
+		return error('Number of input columns is not a multiple of three')
+	}
+	r := rows.len / 4
+	c := rows[0].len / 3
+	mut builder := strings.new_builder(r * (c + 1) - 1)
+	for i in 0 .. r {
+		for j in 0 .. c {
+			top := 4 * i
+			left := 3 * j
+			right := 3 * (j + 1)
+			first := rows[top][left..right]
+			second := rows[top + 1][left..right]
+			third := rows[top + 2][left..right]
+			fourth := rows[top + 3][left..right]
+			builder.write_rune(convert_digit(first, second, third, fourth))
+		}
+		if i + 1 < r {
+			builder.write_rune(`,`)
+		}
+	}
+	return builder.str()
+}

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

@@ -0,0 +1,54 @@
+# 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.
+
+[5ee54e1a-b554-4bf3-a056-9a7976c3f7e8]
+description = "Recognizes 0"
+
+[027ada25-17fd-4d78-aee6-35a19623639d]
+description = "Recognizes 1"
+
+[3cce2dbd-01d9-4f94-8fae-419a822e89bb]
+description = "Unreadable but correctly sized inputs return ?"
+
+[cb19b733-4e36-4cf9-a4a1-6e6aac808b9a]
+description = "Input with a number of lines that is not a multiple of four raises an error"
+
+[235f7bd1-991b-4587-98d4-84206eec4cc6]
+description = "Input with a number of columns that is not a multiple of three raises an error"
+
+[4a841794-73c9-4da9-a779-1f9837faff66]
+description = "Recognizes 110101100"
+
+[70c338f9-85b1-4296-a3a8-122901cdfde8]
+description = "Garbled numbers in a string are replaced with ?"
+
+[ea494ff4-3610-44d7-ab7e-72fdef0e0802]
+description = "Recognizes 2"
+
+[1acd2c00-412b-4268-93c2-bd7ff8e05a2c]
+description = "Recognizes 3"
+
+[eaec6a15-be17-4b6d-b895-596fae5d1329]
+description = "Recognizes 4"
+
+[440f397a-f046-4243-a6ca-81ab5406c56e]
+description = "Recognizes 5"
+
+[f4c9cf6a-f1e2-4878-bfc3-9b85b657caa0]
+description = "Recognizes 6"
+
+[e24ebf80-c611-41bb-a25a-ac2c0f232df5]
+description = "Recognizes 7"
+
+[b79cad4f-e264-4818-9d9e-77766792e233]
+description = "Recognizes 8"
+
+[5efc9cfc-9227-4688-b77d-845049299e66]
+description = "Recognizes 9"
+
+[f60cb04a-42be-494e-a535-3451c8e097a4]
+description = "Recognizes string of decimal numbers"
+
+[b73ecf8b-4423-4b36-860d-3710bdb8a491]
+description = "Numbers separated by empty lines are recognized. Lines are joined by commas."

exercises/practice/ocr-numbers/ocr-numbers.v

@@ -0,0 +1,4 @@
+module main
+
+fn convert(rows []string) !string {
+}