From 528850a6dc971988302f48ddead6b6e04b07fb20 Mon Sep 17 00:00:00 2001
From: resu-xuniL <linux@lavache.com>
Date: Wed, 16 Sep 2026 11:12:34 +0200
Subject: [PATCH 1/4] Generate exercice files with `configlet create`

---
 config.json                                   |  8 ++++
 .../relative-distance/.docs/instructions.md   | 39 +++++++++++++++++++
 .../relative-distance/.docs/introduction.md   | 12 ++++++
 .../relative-distance/.meta/config.json       | 17 ++++++++
 .../relative-distance/.meta/example.php       |  0
 .../relative-distance/.meta/tests.toml        | 31 +++++++++++++++
 .../relative-distance/RelativeDistance.php    |  0
 .../RelativeDistanceTest.php                  |  0
 8 files changed, 107 insertions(+)
 create mode 100644 exercises/practice/relative-distance/.docs/instructions.md
 create mode 100644 exercises/practice/relative-distance/.docs/introduction.md
 create mode 100644 exercises/practice/relative-distance/.meta/config.json
 create mode 100644 exercises/practice/relative-distance/.meta/example.php
 create mode 100644 exercises/practice/relative-distance/.meta/tests.toml
 create mode 100644 exercises/practice/relative-distance/RelativeDistance.php
 create mode 100644 exercises/practice/relative-distance/RelativeDistanceTest.php

diff --git a/config.json b/config.json
index aeba2635c..f187cfaea 100644
--- a/config.json
+++ b/config.json
@@ -1394,6 +1394,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 7
+      },
+      {
+        "slug": "relative-distance",
+        "name": "Relative Distance",
+        "uuid": "d63fd448-07ec-4884-a9fd-64763be95378",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 1
       }
     ],
     "foregone": [
diff --git a/exercises/practice/relative-distance/.docs/instructions.md b/exercises/practice/relative-distance/.docs/instructions.md
new file mode 100644
index 000000000..64ca4e437
--- /dev/null
+++ b/exercises/practice/relative-distance/.docs/instructions.md
@@ -0,0 +1,39 @@
+# Instructions
+
+Your task is to determine the degree of separation between two individuals in a family tree.
+This is similar to the pop culture idea that every Hollywood actor is [within six degrees of Kevin Bacon][six-bacons].
+
+- You will be given an input, with all parent names and their children.
+- Each name is unique, a child _can_ have one or two parents.
+- The degree of separation is defined as the shortest number of connections from one person to another.
+- If two individuals are not connected, return a value that represents "no known relationship."
+  Please see the test cases for the actual implementation.
+
+## Example
+
+Given the following family tree:
+
+```text
+      ┌──────────┐            ┌──────────┐     ┌───────────┐
+      │  Helena  │            │  Erdős   ├─────┤  Shusaku  │
+      └───┬───┬──┘            └─────┬────┘     └────┬──────┘
+      ┌───┘   └───────┐             └───────┬───────┘
+┌─────┴────┐     ┌────┴───┐           ┌─────┴────┐
+│   Isla   ├─────┤ Tariq  │           │   Kevin  │
+└────┬─────┘     └────┬───┘           └──────────┘
+     │                │
+┌────┴────┐      ┌────┴───┐
+│   Uma   │      │ Morphy │
+└─────────┘      └────────┘
+```
+
+The degree of separation between Tariq and Uma is 2 (Tariq → Isla → Uma).
+There's no known relationship between Isla and Kevin, as there is no connection in the given data.
+The degree of separation between Uma and Isla is 1.
+
+~~~~exercism/note
+Isla and Tariq are siblings and have a separation of 1.
+Similarly, this implementation would report a separation of 2 from you to your father's brother.
+~~~~
+
+[six-bacons]: https://en.wikipedia.org/wiki/Six_Degrees_of_Kevin_Bacon
diff --git a/exercises/practice/relative-distance/.docs/introduction.md b/exercises/practice/relative-distance/.docs/introduction.md
new file mode 100644
index 000000000..34073b40a
--- /dev/null
+++ b/exercises/practice/relative-distance/.docs/introduction.md
@@ -0,0 +1,12 @@
+# Introduction
+
+You've been hired to develop **Noble Knots**, the hottest new dating app for nobility!
+With centuries of royal intermarriage, things have gotten… _complicated_.
+To avoid any _oops-we're-twins_ situations, your job is to build a system that checks how closely two people are related.
+
+Noble Knots is inspired by Iceland's "[Islendinga-App][islendiga-app]," which is backed up by a database that traces all known family connections between Icelanders from the time of the settlement of Iceland.
+Your algorithm will determine the **degree of separation** between two individuals in the royal family tree.
+
+Will your app help crown a perfect match?
+
+[islendiga-app]: https://web.archive.org/web/20250816223614/http://www.islendingaapp.is/information-in-english/
diff --git a/exercises/practice/relative-distance/.meta/config.json b/exercises/practice/relative-distance/.meta/config.json
new file mode 100644
index 000000000..c3eb6835a
--- /dev/null
+++ b/exercises/practice/relative-distance/.meta/config.json
@@ -0,0 +1,17 @@
+{
+  "authors": [],
+  "files": {
+    "solution": [
+      "RelativeDistance.php"
+    ],
+    "test": [
+      "RelativeDistanceTest.php"
+    ],
+    "example": [
+      ".meta/example.php"
+    ]
+  },
+  "blurb": "Given a family tree, calculate the degree of separation.",
+  "source": "vaeng",
+  "source_url": "https://github.com/exercism/problem-specifications/pull/2537"
+}
diff --git a/exercises/practice/relative-distance/.meta/example.php b/exercises/practice/relative-distance/.meta/example.php
new file mode 100644
index 000000000..e69de29bb
diff --git a/exercises/practice/relative-distance/.meta/tests.toml b/exercises/practice/relative-distance/.meta/tests.toml
new file mode 100644
index 000000000..66c91ba09
--- /dev/null
+++ b/exercises/practice/relative-distance/.meta/tests.toml
@@ -0,0 +1,31 @@
+# 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.
+
+[4a1ded74-5d32-47fb-8ae5-321f51d06b5b]
+description = "Direct parent-child relation"
+
+[30d17269-83e9-4f82-a0d7-8ef9656d8dce]
+description = "Sibling relationship"
+
+[8dffa27d-a8ab-496d-80b3-2f21c77648b5]
+description = "Two degrees of separation, grandchild"
+
+[34e56ec1-d528-4a42-908e-020a4606ee60]
+description = "Unrelated individuals"
+
+[93ffe989-bad2-48c4-878f-3acb1ce2611b]
+description = "Complex graph, cousins"
+
+[2cc2e76b-013a-433c-9486-1dbe29bf06e5]
+description = "Complex graph, no shortcut, far removed nephew"
+
+[46c9fbcb-e464-455f-a718-049ea3c7400a]
+description = "Complex graph, some shortcuts, cross-down and cross-up, cousins several times removed, with unrelated family tree"
diff --git a/exercises/practice/relative-distance/RelativeDistance.php b/exercises/practice/relative-distance/RelativeDistance.php
new file mode 100644
index 000000000..e69de29bb
diff --git a/exercises/practice/relative-distance/RelativeDistanceTest.php b/exercises/practice/relative-distance/RelativeDistanceTest.php
new file mode 100644
index 000000000..e69de29bb

From d68b6db8fb350968b3b03ebfb84ad5aa212b578b Mon Sep 17 00:00:00 2001
From: resu-xuniL <linux@lavache.com>
Date: Wed, 16 Sep 2026 15:41:03 +0200
Subject: [PATCH 2/4] Create `test` and `example` files

---
 .../relative-distance/.meta/example.php       |  53 ++++
 .../relative-distance/RelativeDistance.php    |  30 ++
 .../RelativeDistanceTest.php                  | 267 ++++++++++++++++++
 3 files changed, 350 insertions(+)

diff --git a/exercises/practice/relative-distance/.meta/example.php b/exercises/practice/relative-distance/.meta/example.php
index e69de29bb..9edcfe672 100644
--- a/exercises/practice/relative-distance/.meta/example.php
+++ b/exercises/practice/relative-distance/.meta/example.php
@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+function buildNeighborhood(array $familyTree): array
+{
+    $neighbors = [];
+
+    foreach ($familyTree as $parent => $children) {
+        foreach ($children as $child) {
+            $neighbors[$parent][$child] = true;
+            $neighbors[$child][$parent] = true;
+        }
+
+        for ($i = 0; $i < count($children); $i++) {
+            for ($j = $i + 1; $j < count($children); $j++) {
+                $neighbors[$children[$i]][$children[$j]] = true;
+                $neighbors[$children[$j]][$children[$i]] = true;
+            }
+        }
+    }
+
+    return $neighbors;
+}
+
+function degreeOfSeparation(array $familyTree, string $personA, string $personB): int
+{
+    $neighbors = buildNeighborhood($familyTree);
+
+    if (!isset($neighbors[$personA], $neighbors[$personB])) {
+        return -1;
+    }
+
+    $seen  = [$personA => true];
+    $queue = [[$personA, 0]];
+
+    while ($queue) {
+        [$person, $degree] = array_shift($queue);
+
+        if ($person === $personB) {
+            return $degree;
+        }
+
+        foreach (array_keys($neighbors[$person]) as $next) {
+            if (!isset($seen[$next])) {
+                $seen[$next]  = true;
+                $queue[] = [$next, $degree + 1];
+            }
+        }
+    }
+
+    return -1;
+}
diff --git a/exercises/practice/relative-distance/RelativeDistance.php b/exercises/practice/relative-distance/RelativeDistance.php
index e69de29bb..0ac94d5ea 100644
--- a/exercises/practice/relative-distance/RelativeDistance.php
+++ b/exercises/practice/relative-distance/RelativeDistance.php
@@ -0,0 +1,30 @@
+<?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);
+
+function degreeOfSeparation(array $familyTree, string $personA, string $personB): int
+{
+    throw new \BadFunctionCallException("Implement the degreeOfSeparation function");
+}
diff --git a/exercises/practice/relative-distance/RelativeDistanceTest.php b/exercises/practice/relative-distance/RelativeDistanceTest.php
index e69de29bb..42da6e58a 100644
--- a/exercises/practice/relative-distance/RelativeDistanceTest.php
+++ b/exercises/practice/relative-distance/RelativeDistanceTest.php
@@ -0,0 +1,267 @@
+<?php
+
+declare(strict_types=1);
+
+use PHPUnit\Framework\Attributes\TestDox;
+use PHPUnit\Framework\TestCase;
+
+class RelativeDistanceTest extends TestCase
+{
+    public static function setUpBeforeClass(): void
+    {
+        require_once 'RelativeDistance.php';
+    }
+
+    /**
+     * uuid 4a1ded74-5d32-47fb-8ae5-321f51d06b5b
+     */
+    #[TestDox('Direct parent-child relation')]
+    public function testDirectParentChildRelation(): void
+    {
+        $familyTree = [
+            "Vera"   => ["Tomoko"],
+            "Tomoko" => ["Aditi"]
+        ];
+        $expected = 1;
+
+        $this->assertEquals($expected, degreeOfSeparation($familyTree, "Vera", "Tomoko"));
+    }
+
+    /**
+     * uuid 30d17269-83e9-4f82-a0d7-8ef9656d8dce
+     */
+    #[TestDox('Sibling relationship')]
+    public function testSiblingRelationship(): void
+    {
+        $familyTree = [
+            "Dalia" => ["Olga", "Yassin"]
+        ];
+        $expected = 1;
+
+        $this->assertEquals($expected, degreeOfSeparation($familyTree, "Olga", "Yassin"));
+    }
+
+    /**
+     * uuid 8dffa27d-a8ab-496d-80b3-2f21c77648b5
+     */
+    #[TestDox('Two degrees of separation, grandchild')]
+    public function testTwoDegreesOfSeparationGrandchild(): void
+    {
+        $familyTree = [
+            "Khadija" => ["Mateo"],
+            "Mateo"   => ["Rami"]
+        ];
+        $expected = 2;
+
+        $this->assertEquals($expected, degreeOfSeparation($familyTree, "Khadija", "Rami"));
+    }
+
+    /**
+     * uuid 34e56ec1-d528-4a42-908e-020a4606ee60
+     */
+    #[TestDox('Unrelated individuals')]
+    public function testUnrelatedIndividuals(): void
+    {
+        $familyTree = [
+            "Priya" => ["Rami"],
+            "Kaito" => ["Elif"]
+        ];
+        $expected = -1;
+
+        $this->assertEquals($expected, degreeOfSeparation($familyTree, "Priya", "Kaito"));
+    }
+
+    /**
+     * uuid 93ffe989-bad2-48c4-878f-3acb1ce2611b
+     */
+    #[TestDox('Complex graph, cousins')]
+    public function testComplexGraphCousins(): void
+    {
+        $familyTree = [
+            "Aiko"    => ["Bao", "Carlos"],
+            "Bao"     => ["Dalia", "Elias"],
+            "Carlos"  => ["Fatima", "Gustavo"],
+            "Dalia"   => ["Hassan", "Isla"],
+            "Elias"   => ["Javier"],
+            "Fatima"  => ["Khadija", "Liam"],
+            "Gustavo" => ["Mina"],
+            "Hassan"  => ["Noah", "Olga"],
+            "Isla"    => ["Pedro"],
+            "Javier"  => ["Quynh", "Ravi"],
+            "Khadija" => ["Sofia"],
+            "Liam"    => ["Tariq", "Uma"],
+            "Mina"    => ["Viktor", "Wang"],
+            "Noah"    => ["Xiomara"],
+            "Olga"    => ["Yuki"],
+            "Pedro"   => ["Zane", "Aditi"],
+            "Quynh"   => ["Boris"],
+            "Ravi"    => ["Celine"],
+            "Sofia"   => ["Diego", "Elif"],
+            "Tariq"   => ["Farah"],
+            "Uma"     => ["Giorgio"],
+            "Viktor"  => ["Hana", "Ian"],
+            "Wang"    => ["Jing"],
+            "Xiomara" => ["Kaito"],
+            "Yuki"    => ["Leila"],
+            "Zane"    => ["Mateo"],
+            "Aditi"   => ["Nia"],
+            "Boris"   => ["Oscar"],
+            "Celine"  => ["Priya"],
+            "Diego"   => ["Qi"],
+            "Elif"    => ["Rami"],
+            "Farah"   => ["Sven"],
+            "Giorgio" => ["Tomoko"],
+            "Hana"    => ["Umar"],
+            "Ian"     => ["Vera"],
+            "Jing"    => ["Wyatt"],
+            "Kaito"   => ["Xia"],
+            "Leila"   => ["Yassin"],
+            "Mateo"   => ["Zara"],
+            "Nia"     => ["Antonio"],
+            "Oscar"   => ["Bianca"],
+            "Priya"   => ["Cai"],
+            "Qi"      => ["Dimitri"],
+            "Rami"    => ["Ewa"],
+            "Sven"    => ["Fabio"],
+            "Tomoko"  => ["Gabriela"],
+            "Umar"    => ["Helena"],
+            "Vera"    => ["Igor"],
+            "Wyatt"   => ["Jun"],
+            "Xia"     => ["Kim"],
+            "Yassin"  => ["Lucia"],
+            "Zara"    => ["Mohammed"]
+        ];
+        $expected = 9;
+
+        $this->assertEquals($expected, degreeOfSeparation($familyTree, "Dimitri", "Fabio"));
+    }
+
+    /**
+     * uuid 2cc2e76b-013a-433c-9486-1dbe29bf06e5
+     */
+    #[TestDox('Complex graph, no shortcut, far removed nephew')]
+    public function testComplexGraphNoShortcutFarRemovedNephew(): void
+    {
+        $familyTree = [
+            "Aiko"    => ["Bao", "Carlos"],
+            "Bao"     => ["Dalia", "Elias"],
+            "Carlos"  => ["Fatima", "Gustavo"],
+            "Dalia"   => ["Hassan", "Isla"],
+            "Elias"   => ["Javier"],
+            "Fatima"  => ["Khadija", "Liam"],
+            "Gustavo" => ["Mina"],
+            "Hassan"  => ["Noah", "Olga"],
+            "Isla"    => ["Pedro"],
+            "Javier"  => ["Quynh", "Ravi"],
+            "Khadija" => ["Sofia"],
+            "Liam"    => ["Tariq", "Uma"],
+            "Mina"    => ["Viktor", "Wang"],
+            "Noah"    => ["Xiomara"],
+            "Olga"    => ["Yuki"],
+            "Pedro"   => ["Zane", "Aditi"],
+            "Quynh"   => ["Boris"],
+            "Ravi"    => ["Celine"],
+            "Sofia"   => ["Diego", "Elif"],
+            "Tariq"   => ["Farah"],
+            "Uma"     => ["Giorgio"],
+            "Viktor"  => ["Hana", "Ian"],
+            "Wang"    => ["Jing"],
+            "Xiomara" => ["Kaito"],
+            "Yuki"    => ["Leila"],
+            "Zane"    => ["Mateo"],
+            "Aditi"   => ["Nia"],
+            "Boris"   => ["Oscar"],
+            "Celine"  => ["Priya"],
+            "Diego"   => ["Qi"],
+            "Elif"    => ["Rami"],
+            "Farah"   => ["Sven"],
+            "Giorgio" => ["Tomoko"],
+            "Hana"    => ["Umar"],
+            "Ian"     => ["Vera"],
+            "Jing"    => ["Wyatt"],
+            "Kaito"   => ["Xia"],
+            "Leila"   => ["Yassin"],
+            "Mateo"   => ["Zara"],
+            "Nia"     => ["Antonio"],
+            "Oscar"   => ["Bianca"],
+            "Priya"   => ["Cai"],
+            "Qi"      => ["Dimitri"],
+            "Rami"    => ["Ewa"],
+            "Sven"    => ["Fabio"],
+            "Tomoko"  => ["Gabriela"],
+            "Umar"    => ["Helena"],
+            "Vera"    => ["Igor"],
+            "Wyatt"   => ["Jun"],
+            "Xia"     => ["Kim"],
+            "Yassin"  => ["Lucia"],
+            "Zara"    => ["Mohammed"]
+        ];
+        $expected = 14;
+
+        $this->assertEquals($expected, degreeOfSeparation($familyTree, "Lucia", "Jun"));
+    }
+
+    /**
+     * uuid 46c9fbcb-e464-455f-a718-049ea3c7400a
+     */
+    #[TestDox('Complex graph, some shortcuts, cross-down and cross-up, cousins several times removed, with unrelated family tree')]
+    public function testComplexGraphSomeShortcutsCrossDownAndCrossUpCousinsSeveralTimesRemovedWithUnrelatedFamilyTree(): void
+    {
+        $familyTree = [
+            "Aiko"    => ["Bao", "Carlos"],
+            "Bao"     => ["Dalia"],
+            "Carlos"  => ["Fatima", "Gustavo"],
+            "Dalia"   => ["Hassan", "Isla"],
+            "Fatima"  => ["Khadija", "Liam"],
+            "Gustavo" => ["Mina"],
+            "Hassan"  => ["Noah", "Olga"],
+            "Isla"    => ["Pedro"],
+            "Javier"  => ["Quynh", "Ravi"],
+            "Khadija" => ["Sofia"],
+            "Liam"    => ["Tariq", "Uma"],
+            "Mina"    => ["Viktor", "Wang"],
+            "Noah"    => ["Xiomara"],
+            "Olga"    => ["Yuki"],
+            "Pedro"   => ["Zane", "Aditi"],
+            "Quynh"   => ["Boris"],
+            "Ravi"    => ["Celine"],
+            "Sofia"   => ["Diego", "Elif"],
+            "Tariq"   => ["Farah"],
+            "Uma"     => ["Giorgio"],
+            "Viktor"  => ["Hana", "Ian"],
+            "Wang"    => ["Jing"],
+            "Xiomara" => ["Kaito"],
+            "Yuki"    => ["Leila"],
+            "Zane"    => ["Mateo"],
+            "Aditi"   => ["Nia"],
+            "Boris"   => ["Oscar"],
+            "Celine"  => ["Priya"],
+            "Diego"   => ["Qi"],
+            "Elif"    => ["Rami"],
+            "Farah"   => ["Sven"],
+            "Giorgio" => ["Tomoko"],
+            "Hana"    => ["Umar"],
+            "Ian"     => ["Vera"],
+            "Jing"    => ["Wyatt"],
+            "Kaito"   => ["Xia"],
+            "Leila"   => ["Yassin"],
+            "Mateo"   => ["Zara"],
+            "Nia"     => ["Antonio"],
+            "Oscar"   => ["Bianca"],
+            "Priya"   => ["Cai"],
+            "Qi"      => ["Dimitri"],
+            "Rami"    => ["Ewa"],
+            "Sven"    => ["Fabio"],
+            "Tomoko"  => ["Gabriela"],
+            "Umar"    => ["Helena"],
+            "Vera"    => ["Igor"],
+            "Wyatt"   => ["Jun"],
+            "Xia"     => ["Kim"],
+            "Yassin"  => ["Lucia"],
+            "Zara"    => ["Mohammed"]
+        ];
+        $expected = 12;
+
+        $this->assertEquals($expected, degreeOfSeparation($familyTree, "Wyatt", "Xia"));
+    }
+}

From 64a54e603e693c296726e8a13850a9dfbf8821fe Mon Sep 17 00:00:00 2001
From: resu-xuniL <linux@lavache.com>
Date: Fri, 18 Sep 2026 08:57:11 +0200
Subject: [PATCH 3/4] Set the difficulty rank to `4`

---
 config.json | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/config.json b/config.json
index f187cfaea..1ef332ef2 100644
--- a/config.json
+++ b/config.json
@@ -1093,6 +1093,14 @@
           "transforming"
         ]
       },
+      {
+        "slug": "relative-distance",
+        "name": "Relative Distance",
+        "uuid": "d63fd448-07ec-4884-a9fd-64763be95378",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "roman-numerals",
         "name": "Roman Numerals",
@@ -1394,14 +1402,6 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 7
-      },
-      {
-        "slug": "relative-distance",
-        "name": "Relative Distance",
-        "uuid": "d63fd448-07ec-4884-a9fd-64763be95378",
-        "practices": [],
-        "prerequisites": [],
-        "difficulty": 1
       }
     ],
     "foregone": [

From dab8f75963cbd1a1684a8b0db817133dcac99459 Mon Sep 17 00:00:00 2001
From: resu-xuniL <linux@lavache.com>
Date: Fri, 18 Sep 2026 08:58:07 +0200
Subject: [PATCH 4/4] Add GitHub handle to `config.json`

---
 exercises/practice/relative-distance/.meta/config.json | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/exercises/practice/relative-distance/.meta/config.json b/exercises/practice/relative-distance/.meta/config.json
index c3eb6835a..b3ad31bbc 100644
--- a/exercises/practice/relative-distance/.meta/config.json
+++ b/exercises/practice/relative-distance/.meta/config.json
@@ -1,5 +1,7 @@
 {
-  "authors": [],
+  "authors": [
+    "resu-xuniL"
+  ],
   "files": {
     "solution": [
       "RelativeDistance.php"