Add Eliuds Eggs exercise (#639)

Author: homersimpsons

config.json

@@ -1227,6 +1227,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 5
+      },
+      {
+        "slug": "eliuds-eggs",
+        "name": "Eliud's Eggs",
+        "uuid": "9a8df843-8805-4287-b863-b8123defc266",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
       }
     ]
   },

exercises/practice/eliuds-eggs/.docs/instructions.append.md

@@ -0,0 +1,13 @@
+## Bitwise operators
+
+In PHP there are [bitwise operators](https://www.php.net/manual/en/language.operators.bitwise.php).
+
+For example, the "bitwise and" operator (`&`) can be used to check that a bit of a number is defined:
+```php
+$number = 89; // 0b01011001
+$mask16 = 16; // 0b00010000
+$mask32 = 32; // 0b00100000
+
+$isMask16 = ($number & $mask16) > 0; // 0b00010000 > 0 => TRUE
+$isMask32 = ($number & $mask32) > 0; // 0b00000000 > 0 => FALSE
+```

exercises/practice/eliuds-eggs/.docs/instructions.md

@@ -0,0 +1,8 @@
+# Instructions
+
+Your task is to count the number of 1 bits in the binary representation of a number.
+
+## Restrictions
+
+Keep your hands off that bit-count functionality provided by your standard library!
+Solve this one yourself using other basic tools instead.

exercises/practice/eliuds-eggs/.docs/introduction.md

@@ -0,0 +1,47 @@
+# Introduction
+
+Your friend Eliud inherited a farm from her grandma Tigist.
+Her granny was an inventor and had a tendency to build things in an overly complicated manner.
+The chicken coop has a digital display showing an encoded number representing the positions of all eggs that could be picked up.
+
+Eliud is asking you to write a program that shows the actual number of eggs in the coop.
+
+The position information encoding is calculated as follows:
+
+1. Scan the potential egg-laying spots and mark down a `1` for an existing egg or a `0` for an empty spot.
+2. Convert the number from binary to decimal.
+3. Show the result on the display.
+
+Example 1:
+
+```text
+Chicken Coop:
+ _ _ _ _ _ _ _
+|E| |E|E| | |E|
+
+Resulting Binary:
+ 1 0 1 1 0 0 1
+
+Decimal number on the display:
+89
+
+Actual eggs in the coop:
+4
+```
+
+Example 2:
+
+```text
+Chicken Coop:
+ _ _ _ _ _ _ _ _
+| | | |E| | | | |
+
+Resulting Binary:
+ 0 0 0 1 0 0 0 0
+
+Decimal number on the display:
+16
+
+Actual eggs in the coop:
+1
+```

exercises/practice/eliuds-eggs/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "homersimpsons"
+  ],
+  "files": {
+    "solution": [
+      "EliudsEggs.php"
+    ],
+    "test": [
+      "EliudsEggsTest.php"
+    ],
+    "example": [
+      ".meta/example.php"
+    ]
+  },
+  "blurb": "Help Eliud count the number of eggs in her chicken coop by counting the number of 1 bits in a binary representation.",
+  "source": "Christian Willner, Eric Willigers",
+  "source_url": "https://forum.exercism.org/t/new-exercise-suggestion-pop-count/7632/5"
+}

exercises/practice/eliuds-eggs/.meta/example.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+class EliudsEggs
+{
+    public function eggCount(int $displayValue): int
+    {
+        if ($displayValue === 0) {
+            return 0;
+        }
+
+        return ($displayValue & 1) + $this->eggCount($displayValue >> 1);
+    }
+}

exercises/practice/eliuds-eggs/.meta/tests.toml

@@ -0,0 +1,22 @@
+# 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.
+
+[559e789d-07d1-4422-9004-3b699f83bca3]
+description = "0 eggs"
+
+[97223282-f71e-490c-92f0-b3ec9e275aba]
+description = "1 egg"
+
+[1f8fd18f-26e9-4144-9a0e-57cdfc4f4ff5]
+description = "4 eggs"
+
+[0c18be92-a498-4ef2-bcbb-28ac4b06cb81]
+description = "13 eggs"

exercises/practice/eliuds-eggs/EliudsEggs.php

@@ -0,0 +1,33 @@
+<?php
+
+/*
+ * By adding type hints and enabling strict type checking, code can become
+ * easier to read, self-documenting and reduce the number of potential bugs.
+ * By default, type declarations are non-strict, which means they will attempt
+ * to change the original type to match the type specified by the
+ * type-declaration.
+ *
+ * In other words, if you pass a string to a function requiring a float,
+ * it will attempt to convert the string value to a float.
+ *
+ * To enable strict mode, a single declare directive must be placed at the top
+ * of the file.
+ * This means that the strictness of typing is configured on a per-file basis.
+ * This directive not only affects the type declarations of parameters, but also
+ * a function's return type.
+ *
+ * For more info review the Concept on strict type checking in the PHP track
+ * <link>.
+ *
+ * To disable strict typing, comment out the directive below.
+ */
+
+declare(strict_types=1);
+
+class EliudsEggs
+{
+    public function eggCount(int $displayValue): int
+    {
+        throw new \BadMethodCallException("Implement the eggCount function");
+    }
+}

exercises/practice/eliuds-eggs/EliudsEggsTest.php

@@ -0,0 +1,73 @@
+<?php
+
+/*
+ * By adding type hints and enabling strict type checking, code can become
+ * easier to read, self-documenting and reduce the number of potential bugs.
+ * By default, type declarations are non-strict, which means they will attempt
+ * to change the original type to match the type specified by the
+ * type-declaration.
+ *
+ * In other words, if you pass a string to a function requiring a float,
+ * it will attempt to convert the string value to a float.
+ *
+ * To enable strict mode, a single declare directive must be placed at the top
+ * of the file.
+ * This means that the strictness of typing is configured on a per-file basis.
+ * This directive not only affects the type declarations of parameters, but also
+ * a function's return type.
+ *
+ * For more info review the Concept on strict type checking in the PHP track
+ * <link>.
+ *
+ * To disable strict typing, comment out the directive below.
+ */
+
+declare(strict_types=1);
+
+class EliudsEggsTest extends PHPUnit\Framework\TestCase
+{
+    public static function setUpBeforeClass(): void
+    {
+        require_once 'EliudsEggs.php';
+    }
+
+    /**
+     * uuid: 559e789d-07d1-4422-9004-3b699f83bca3
+     * @testdox 0 eggs
+     */
+    public function test0Eggs()
+    {
+        $eliudsEggs = new EliudsEggs();
+        $this->assertEquals(0, $eliudsEggs->eggCount(0));
+    }
+
+    /**
+     * uuid: 97223282-f71e-490c-92f0-b3ec9e275aba
+     * @testdox 1 eggs
+     */
+    public function test1Eggs()
+    {
+        $eliudsEggs = new EliudsEggs();
+        $this->assertEquals(1, $eliudsEggs->eggCount(16));
+    }
+
+    /**
+     * uuid: 1f8fd18f-26e9-4144-9a0e-57cdfc4f4ff5
+     * @testdox 4 eggs
+     */
+    public function test4Eggs()
+    {
+        $eliudsEggs = new EliudsEggs();
+        $this->assertEquals(4, $eliudsEggs->eggCount(89));
+    }
+
+    /**
+     * uuid: 0c18be92-a498-4ef2-bcbb-28ac4b06cb81
+     * @testdox 13 eggs
+     */
+    public function test13Eggs()
+    {
+        $eliudsEggs = new EliudsEggs();
+        $this->assertEquals(13, $eliudsEggs->eggCount(2000000000));
+    }
+}