- Create dataset coding interview with unit test

- Add readme on dataset coding interview (WIP)

src/DataSet/DataSet.php

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+<?php
+
+namespace Ianriizky\CodingInterview\DataSet;
+
+use SplFixedArray;
+
+class DataSet
+{
+    /**
+     * Current size of the collection.
+     *
+     * @var int
+     */
+    protected int $size = 0;
+
+    /**
+     * Collection of the data set.
+     *
+     * @var \SplFixedArray
+     */
+    protected SplFixedArray $collection;
+
+    /**
+     * Create a new instance class.
+     *
+     * @param  int  $initialSize
+     * @return void
+     */
+    public function __construct(int $initialSize = 10)
+    {
+        $this->collection = new SplFixedArray($initialSize);
+    }
+
+    /**
+     * Add a value to the collection.
+     *
+     * @param  mixed  $value
+     * @return bool
+     */
+    public function add($value): bool
+    {
+        if ($this->contains($value)) {
+            return false;
+        }
+
+        $this->ensureSize();
+
+        $this->collection[$this->size] = $value;
+        $this->size++;
+
+        return true;
+    }
+
+    /**
+     * Determine whether the given value is exists on the collection or not.
+     *
+     * @param  mixed  $value
+     * @return bool
+     */
+    public function contains($value): bool
+    {
+        foreach ($this->collection as $item) {
+            if ($value === $item) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Return size of collection.
+     *
+     * @return int
+     */
+    public function size(): int
+    {
+        return $this->size;
+    }
+
+    /**
+     * Return collection of the data set.
+     *
+     * @return \SplFixedArray
+     */
+    public function collection(): SplFixedArray
+    {
+        return $this->collection;
+    }
+
+    /**
+     * Remove a value from the collection.
+     *
+     * @param  mixed  $value
+     * @return bool
+     */
+    public function remove($value): bool
+    {
+        if (!$this->contains($value)) {
+            return false;
+        }
+
+        $removedIndex = $this->indexOf($value);
+
+        for ($index = $removedIndex; $index <= $this->size; $index++) {
+            $this->collection[$index] = $this->collection[$index + 1];
+        }
+
+        $this->size--;
+
+        return true;
+    }
+
+    /**
+     * Return index of given value.
+     *
+     * @param  mixed  $value
+     * @return int
+     */
+    protected function indexOf($value): int
+    {
+        for ($index = 0; $index < $this->collection->count(); $index++) {
+            if ($value === $this->collection[$index]) {
+                return $index;
+            }
+        }
+
+        return -1;
+    }
+
+    /**
+     * Ensure that the data set size is enough to contain the collection.
+     *
+     * @return void
+     */
+    protected function ensureSize(): void
+    {
+        if ($this->size < $this->collection->count()) {
+            return;
+        }
+
+        $tempCollection = new SplFixedArray($this->size + 1);
+
+        for ($index = 0; $index < $this->collection->count(); $index++) {
+            $tempCollection[$index] = $this->collection[$index];
+        }
+
+        $this->collection = $tempCollection;
+    }
+}

src/DataSet/README.md

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+# Data Set
+
+Data Set adalah ... <sup id="pg1">[1](#fn1)</sup>.
+
+Berikut ini adalah contoh *source code* dari studi kasus Data Set menggunakan bahasa pemrograman PHP <sup id="pg2">[2](#fn2)</sup>. Detail lengkapnya bisa dilihat [di sini](DataSet.php).
+```php
+///
+```
+
+---
+### Catatan Kaki:
+
+<strong id="fn1">1</strong> [Data set, Wikipedia](https://en.wikipedia.org/wiki/Data_set). [↩](#pg1)
+<br>
+<strong id="fn2">2</strong> [Programmer Zaman Now - Coding Interview Struktur Data Set](https://www.youtube.com/watch?v=OWm1vSHrC_A). [↩](#pg2)
+<br>

tests/Unit/DataSetTest.php

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+<?php
+
+namespace Tests\Unit;
+
+use Ianriizky\CodingInterview\DataSet\DataSet;
+use Tests\TestCase;
+
+class DataSetTest extends TestCase
+{
+    /**
+     * Assert that data set add() method is run correctly.
+     *
+     * @return void
+     */
+    public function test_add()
+    {
+        $dataset = new DataSet;
+
+        $this->assertTrue($dataset->add('Septianata'));
+        $this->assertFalse($dataset->add('Septianata'));
+
+        $this->assertTrue($dataset->add('Rizky'));
+        $this->assertFalse($dataset->add('Rizky'));
+
+        $this->assertTrue($dataset->add('Pratama'));
+        $this->assertFalse($dataset->add('Pratama'));
+    }
+
+    /**
+     * Assert that data set contains() method is run correctly.
+     *
+     * @return void
+     */
+    public function test_contains()
+    {
+        $dataset = new DataSet;
+
+        $dataset->add('Septianata');
+        $dataset->add('Rizky');
+
+        $this->assertTrue($dataset->contains('Septianata'));
+        $this->assertTrue($dataset->contains('Rizky'));
+        $this->assertFalse($dataset->contains('Pratama'));
+    }
+
+    /**
+     * Assert that data set size() method is run correctly.
+     *
+     * @return void
+     */
+    public function test_size()
+    {
+        $dataset = new DataSet;
+        $this->assertEquals($dataset->size(), 0);
+
+        $dataset->add('Septianata');
+        $this->assertEquals($dataset->size(), 1);
+
+        $dataset->add('Septianata');
+        $this->assertEquals($dataset->size(), 1);
+
+        $dataset->add('Rizky');
+        $this->assertEquals($dataset->size(), 2);
+    }
+
+    /**
+     * Assert that data set remove() method is run correctly.
+     *
+     * @return void
+     */
+    public function test_remove()
+    {
+        $dataset = new DataSet;
+
+        $dataset->add('Septianata');
+        $dataset->add('Rizky');
+        $dataset->add('Pratama');
+        $dataset->add('Belajar');
+        $dataset->add('Data Set');
+        $dataset->add('PHP');
+
+        $this->assertEquals(6, $dataset->size());
+
+        $dataset->remove('Rizky');
+
+        $this->assertEquals(5, $dataset->size());
+
+        $this->assertTrue($dataset->contains('Septianata'));
+        $this->assertTrue($dataset->contains('Pratama'));
+        $this->assertTrue($dataset->contains('Belajar'));
+        $this->assertTrue($dataset->contains('Data Set'));
+        $this->assertTrue($dataset->contains('PHP'));
+    }
+
+    /**
+     * Assert that data set growth() method is run correctly.
+     *
+     * @return void
+     */
+    public function test_growth()
+    {
+        $size = rand(1, 100);
+        $dataset = new DataSet;
+
+        for ($index = 0; $index < $size; $index++) {
+            $dataset->add('item-' . $index);
+        }
+
+        $this->assertEquals($size, $dataset->size());
+    }
+}