Add twelve-days exercise (#436)

config.json

@@ -60,9 +60,17 @@
         ],
         "difficulty": 1
       },
+      {
+        "slug": "twelve-days",
+        "name": "Twelve Days",
+        "uuid": "1ae61ecf-2ce4-49bb-9e3f-8b8b7125b176",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "eliuds-eggs",
-        "name": "Eliuds Eggs",
+        "name": "Eliud's Eggs",
         "uuid": "493be46b-6cb3-4591-87db-b0a17e9238ee",
         "practices": [],
         "prerequisites": [],

exercises/practice/twelve-days/.docs/instructions.md

@@ -0,0 +1,36 @@
+# Instructions
+
+Your task in this exercise is to write code that returns the lyrics of the song: "The Twelve Days of Christmas."
+
+"The Twelve Days of Christmas" is a common English Christmas carol.
+Each subsequent verse of the song builds on the previous verse.
+
+The lyrics your code returns should _exactly_ match the full song text shown below.
+
+## Lyrics
+
+```text
+On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.
+
+On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+```

exercises/practice/twelve-days/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "twelve_days.zig"
+    ],
+    "test": [
+      "test_twelve_days.zig"
+    ],
+    "example": [
+      ".meta/example.zig"
+    ]
+  },
+  "blurb": "Output the lyrics to 'The Twelve Days of Christmas'.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/The_Twelve_Days_of_Christmas_(song)"
+}

exercises/practice/twelve-days/.meta/example.zig

@@ -0,0 +1,37 @@
+const std = @import("std");
+
+const on_the = "On the ";
+
+const day_of = " day of Christmas my true love gave to me: ";
+
+const gifts = "twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.";
+
+const ordinals = [_][]const u8{ "", "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth", "ninth", "tenth", "eleventh", "twelfth" };
+
+const table = [_]usize{ 0, 235, 213, 194, 174, 157, 137, 113, 90, 69, 48, 26, 0 };
+
+fn appendString(buffer: []u8, offset: *usize, str: []const u8) void {
+    @memcpy(buffer[offset.*..(offset.* + str.len)], str);
+    offset.* += str.len;
+}
+
+pub fn recite(buffer: []u8, start_verse: u32, end_verse: u32) []const u8 {
+    var offset: usize = 0;
+
+    for (start_verse..end_verse+1) |verse| {
+        if (verse != start_verse) {
+            buffer[offset] = '\n';
+            offset += 1;
+        }
+
+        appendString(buffer, &offset, on_the);
+
+        appendString(buffer, &offset, ordinals[verse]);
+
+        appendString(buffer, &offset, day_of);
+
+        appendString(buffer, &offset, gifts[table[verse]..]);
+    }
+
+    return buffer[0..offset];
+}

exercises/practice/twelve-days/.meta/tests.toml

@@ -0,0 +1,55 @@
+# 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.
+
+[c0b5a5e6-c89d-49b1-a6b2-9f523bff33f7]
+description = "verse -> first day a partridge in a pear tree"
+
+[1c64508a-df3d-420a-b8e1-fe408847854a]
+description = "verse -> second day two turtle doves"
+
+[a919e09c-75b2-4e64-bb23-de4a692060a8]
+description = "verse -> third day three french hens"
+
+[9bed8631-ec60-4894-a3bb-4f0ec9fbe68d]
+description = "verse -> fourth day four calling birds"
+
+[cf1024f0-73b6-4545-be57-e9cea565289a]
+description = "verse -> fifth day five gold rings"
+
+[50bd3393-868a-4f24-a618-68df3d02ff04]
+description = "verse -> sixth day six geese-a-laying"
+
+[8f29638c-9bf1-4680-94be-e8b84e4ade83]
+description = "verse -> seventh day seven swans-a-swimming"
+
+[7038d6e1-e377-47ad-8c37-10670a05bc05]
+description = "verse -> eighth day eight maids-a-milking"
+
+[37a800a6-7a56-4352-8d72-0f51eb37cfe8]
+description = "verse -> ninth day nine ladies dancing"
+
+[10b158aa-49ff-4b2d-afc3-13af9133510d]
+description = "verse -> tenth day ten lords-a-leaping"
+
+[08d7d453-f2ba-478d-8df0-d39ea6a4f457]
+description = "verse -> eleventh day eleven pipers piping"
+
+[0620fea7-1704-4e48-b557-c05bf43967f0]
+description = "verse -> twelfth day twelve drummers drumming"
+
+[da8b9013-b1e8-49df-b6ef-ddec0219e398]
+description = "lyrics -> recites first three verses of the song"
+
+[c095af0d-3137-4653-ad32-bfb899eda24c]
+description = "lyrics -> recites three verses from the middle of the song"
+
+[20921bc9-cc52-4627-80b3-198cbbfcf9b7]
+description = "lyrics -> recites the whole song"

exercises/practice/twelve-days/test_twelve_days.zig

@@ -0,0 +1,169 @@
+const std = @import("std");
+const testing = std.testing;
+
+const twelve_days = @import("twelve_days.zig");
+
+test "verse-first day a partridge in a pear tree" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 1, 1);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-second day two turtle doves" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 2, 2);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-third day three french hens" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 3, 3);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-fourth day four calling birds" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 4, 4);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-fifth day five gold rings" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 5, 5);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-sixth day six geese-a-laying" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 6, 6);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-seventh day seven swans-a-swimming" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 7, 7);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-eighth day eight maids-a-milking" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 8, 8);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-ninth day nine ladies dancing" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 9, 9);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-tenth day ten lords-a-leaping" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 10, 10);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-eleventh day eleven pipers piping" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 11, 11);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "verse-twelfth day twelve drummers drumming" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 12, 12);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "lyrics-recites first three verses of the song" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.
+        \\On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 1, 3);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "lyrics-recites three verses from the middle of the song" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 4, 6);
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "lyrics-recites the whole song" {
+    const buffer_size = 4000;
+    var buffer: [buffer_size]u8 = undefined;
+    const expected: []const u8 =
+        \\On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.
+        \\On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+        \\On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+    ;
+    const actual = twelve_days.recite(&buffer, 1, 12);
+    try testing.expectEqualStrings(expected, actual);
+}

exercises/practice/twelve-days/twelve_days.zig

@@ -0,0 +1,6 @@
+pub fn recite(buffer: []u8, start_verse: u32, end_verse: u32) []const u8 {
+    _ = buffer;
+    _ = start_verse;
+    _ = end_verse;
+    @compileError("please implement the recite function");
+}