Add diamond

config.json

@@ -673,6 +673,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "diamond",
+        "name": "Diamond",
+        "uuid": "f1da1920-802f-4165-87a4-2381f530c262",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "house",
         "name": "House",

exercises/practice/diamond/.docs/instructions.md

@@ -0,0 +1,52 @@
+# Instructions
+
+The diamond kata takes as its input a letter, and outputs it in a diamond shape.
+Given a letter, it prints a diamond starting with 'A', with the supplied letter at the widest point.
+
+## Requirements
+
+- The first row contains one 'A'.
+- The last row contains one 'A'.
+- All rows, except the first and last, have exactly two identical letters.
+- All rows have as many trailing spaces as leading spaces. (This might be 0).
+- The diamond is horizontally symmetric.
+- The diamond is vertically symmetric.
+- The diamond has a square shape (width equals height).
+- The letters form a diamond shape.
+- The top half has the letters in ascending order.
+- The bottom half has the letters in descending order.
+- The four corners (containing the spaces) are triangles.
+
+## Examples
+
+In the following examples, spaces are indicated by `·` characters.
+
+Diamond for letter 'A':
+
+```text
+A
+```
+
+Diamond for letter 'C':
+
+```text
+··A··
+·B·B·
+C···C
+·B·B·
+··A··
+```
+
+Diamond for letter 'E':
+
+```text
+····A····
+···B·B···
+··C···C··
+·D·····D·
+E·······E
+·D·····D·
+··C···C··
+···B·B···
+····A····
+```

exercises/practice/diamond/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "diamond.coffee"
+    ],
+    "test": [
+      "diamond.spec.coffee"
+    ],
+    "example": [
+      ".meta/example.coffee"
+    ]
+  },
+  "blurb": "Given a letter, print a diamond starting with 'A' with the supplied letter at the widest point.",
+  "source": "Seb Rose",
+  "source_url": "https://web.archive.org/web/20220807163751/http://claysnow.co.uk/recycling-tests-in-tdd/"
+}

exercises/practice/diamond/.meta/example.coffee

@@ -0,0 +1,27 @@
+class Diamond
+  @rows: (letter) ->
+    return 'A' if letter is 'A'
+
+    start = 'A'.charCodeAt 0 
+    end = letter.charCodeAt 0
+    size = end - start + 1
+    diamond = []
+
+    # Down to middle of diamond
+    for i in [0...size]
+      currentChar = String.fromCharCode start + i 
+      outer = ' '.repeat size - 1 - i
+      if i is 0
+        line = outer + currentChar + outer
+      else
+        inner = ' '.repeat 2 * i - 1
+        line = outer + currentChar + inner + currentChar + outer
+      diamond.push line
+
+    # flip the diamond to make the bottom half
+    for i in [size-2..0]
+      diamond.push diamond[i]
+
+    diamond.join '\n'
+
+module.exports = Diamond

exercises/practice/diamond/.meta/tests.toml

@@ -0,0 +1,25 @@
+# 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.
+
+[202fb4cc-6a38-4883-9193-a29d5cb92076]
+description = "Degenerate case with a single 'A' row"
+
+[bd6a6d78-9302-42e9-8f60-ac1461e9abae]
+description = "Degenerate case with no row containing 3 distinct groups of spaces"
+
+[af8efb49-14ed-447f-8944-4cc59ce3fd76]
+description = "Smallest non-degenerate case with odd diamond side length"
+
+[e0c19a95-9888-4d05-86a0-fa81b9e70d1d]
+description = "Smallest non-degenerate case with even diamond side length"
+
+[82ea9aa9-4c0e-442a-b07e-40204e925944]
+description = "Largest possible diamond"

exercises/practice/diamond/diamond.coffee

@@ -0,0 +1,4 @@
+class Diamond
+  @rows: (letter) ->
+
+module.exports = Diamond

exercises/practice/diamond/diamond.spec.coffee

@@ -0,0 +1,94 @@
+Diamond = require './diamond'
+
+describe 'Diamond', ->
+  it 'Degenerate case with a single A row', ->
+    expected = [
+      'A'
+    ].join '\n'
+    expect(Diamond.rows 'A').toEqual expected
+
+  xit 'Degenerate case with no row containing 3 distinct groups of spaces', ->
+    expected = [
+      ' A '
+      'B B'
+      ' A '
+    ].join '\n'
+    expect(Diamond.rows 'B').toEqual expected
+
+  xit 'Smallest non-degenerate case with odd diamond side length', ->
+    expected = [
+      '  A  '
+      ' B B '
+      'C   C'
+      ' B B '
+      '  A  '
+    ].join '\n'
+    expect(Diamond.rows 'C').toEqual expected
+
+  xit 'Smallest non-degenerate case with even diamond side length', ->
+    expected = [
+      '   A   '
+      '  B B  '
+      ' C   C '
+      'D     D'
+      ' C   C '
+      '  B B  '
+      '   A   '
+    ].join '\n'
+    expect(Diamond.rows 'D').toEqual expected
+
+  xit 'Largest possible diamond', ->
+    expected = [
+      '                         A                         '
+      '                        B B                        '
+      '                       C   C                       '
+      '                      D     D                      '
+      '                     E       E                     '
+      '                    F         F                    '
+      '                   G           G                   '
+      '                  H             H                  '
+      '                 I               I                 '
+      '                J                 J                '
+      '               K                   K               '
+      '              L                     L              '
+      '             M                       M             '
+      '            N                         N            '
+      '           O                           O           '
+      '          P                             P          '
+      '         Q                               Q         '
+      '        R                                 R        '
+      '       S                                   S       '
+      '      T                                     T      '
+      '     U                                       U     '
+      '    V                                         V    '
+      '   W                                           W   '
+      '  X                                             X  '
+      ' Y                                               Y '
+      'Z                                                 Z'
+      ' Y                                               Y '
+      '  X                                             X  '
+      '   W                                           W   '
+      '    V                                         V    '
+      '     U                                       U     '
+      '      T                                     T      '
+      '       S                                   S       '
+      '        R                                 R        '
+      '         Q                               Q         '
+      '          P                             P          '
+      '           O                           O           '
+      '            N                         N            '
+      '             M                       M             '
+      '              L                     L              '
+      '               K                   K               '
+      '                J                 J                '
+      '                 I               I                 '
+      '                  H             H                  '
+      '                   G           G                   '
+      '                    F         F                    '
+      '                     E       E                     '
+      '                      D     D                      '
+      '                       C   C                       '
+      '                        B B                        '
+      '                         A                         '
+    ].join '\n'
+    expect(Diamond.rows 'Z').toEqual expected