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Add relative distance exercise #748

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a998879
Fixes to concept tree
meatball133 Dec 6, 2024
ca5f72c
Merge branch 'exercism:main' into main
meatball133 Jan 1, 2026
31aa5b6
Merge branch 'exercism:main' into main
meatball133 Jan 3, 2026
cd81933
Add Relative Distance exercise with instructions, examples, and tests
meatball133 Jan 3, 2026
e116964
regenerate test file
meatball133 Jan 3, 2026
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8 changes: 8 additions & 0 deletions config.json
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Expand Up @@ -1060,6 +1060,14 @@
"prerequisites": [],
"difficulty": 4
},
{
"slug": "relative-distance",
"name": "Relative Distance",
"uuid": "6d5cdbb3-f592-4b18-9cd3-23a28723e9cf",
"practices": [],
"prerequisites": [],
"difficulty": 4
},
{
"slug": "flower-field",
"name": "Flower Field",
Expand Down
39 changes: 39 additions & 0 deletions exercises/practice/relative-distance/.docs/instructions.md
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# 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.m.wikipedia.org/wiki/Six_Degrees_of_Kevin_Bacon
12 changes: 12 additions & 0 deletions exercises/practice/relative-distance/.docs/introduction.md
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# 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/
19 changes: 19 additions & 0 deletions exercises/practice/relative-distance/.meta/config.json
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{
"authors": [
"meatball133"
],
"files": {
"solution": [
"src/relative_distance.cr"
],
"test": [
"spec/relative_distance_spec.cr"
],
"example": [
".meta/src/example.cr"
]
},
"blurb": "Given a family tree, calculate the degree of separation.",
"source": "vaeng",
"source_url": "https://github.com/exercism/problem-specifications/pull/2537"
}
63 changes: 63 additions & 0 deletions exercises/practice/relative-distance/.meta/src/example.cr
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require "set"

class RelativeDistance
@graph : Hash(String, Set(String))

def initialize(family_tree : Hash(String, Array(String)))
@family_tree = family_tree
@graph = build_graph(@family_tree)
end

def degree_of_separation?(person_a : String, person_b : String) : Int32?
return 0 if person_a == person_b
return nil unless @graph.has_key?(person_a) && @graph.has_key?(person_b)

visited = Set(String).new
visited << person_a

queue = [{person_a, 0}] of Tuple(String, Int32)
head = 0

while head < queue.size
current, distance = queue[head]
head += 1

@graph[current].each do |neighbor|
next if visited.includes?(neighbor)

next_distance = distance + 1
return next_distance if neighbor == person_b

visited << neighbor
queue << {neighbor, next_distance}
end
end

nil
end

private def build_graph(family_tree : Hash(String, Array(String))) : Hash(String, Set(String))
graph = Hash(String, Set(String)).new { |hash, key| hash[key] = Set(String).new }

family_tree.each do |parent, children|
graph[parent]

children.each do |child|
graph[child]
graph[parent] << child
graph[child] << parent
end

# Siblings are considered 1 degree apart.
children.each_with_index do |child, i|
(i + 1...children.size).each do |j|
sibling = children[j]
graph[child] << sibling
graph[sibling] << child
end
end
end

graph
end
end
12 changes: 12 additions & 0 deletions exercises/practice/relative-distance/.meta/test_template.ecr
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require "spec"
require "../src/*"

describe "<%-= to_capitalized(@json["exercise"].to_s) %>" do
<%- @json["cases"].as_a.each do |cases| %>
<%= status()%> "<%-= cases["description"] %>" do
family_tree = <%= cases["input"]["familyTree"].to_s == "{}" ? "{} of String => Array(String)" : to_s_deep(cases["input"]["familyTree"]) %>
relative_distance = <%= to_capitalized(@json["exercise"].to_s) %>.new(family_tree)
relative_distance.<%= cases["property"].to_s.underscore %>?("<%= cases["input"]["personA"] %>", "<%= cases["input"]["personB"] %>").should eq(<%= cases["expected"].as_i? ? cases["expected"] : "nil" %>)
end
<% end %>
end
31 changes: 31 additions & 0 deletions exercises/practice/relative-distance/.meta/tests.toml
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# 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"
85 changes: 85 additions & 0 deletions exercises/practice/relative-distance/spec/relative_distance_spec.cr
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require "spec"
require "../src/*"

describe "RelativeDistance" do
it "Direct parent-child relation" do
family_tree = {"Vera" => ["Tomoko"], "Tomoko" => ["Aditi"]}
relative_distance = RelativeDistance.new(family_tree)
relative_distance.degree_of_separation?("Vera", "Tomoko").should eq(1)
end

pending "Sibling relationship" do
family_tree = {"Dalia" => ["Olga", "Yassin"]}
relative_distance = RelativeDistance.new(family_tree)
relative_distance.degree_of_separation?("Olga", "Yassin").should eq(1)
end

pending "Two degrees of separation, grandchild" do
family_tree = {"Khadija" => ["Mateo"], "Mateo" => ["Rami"]}
relative_distance = RelativeDistance.new(family_tree)
relative_distance.degree_of_separation?("Khadija", "Rami").should eq(2)
end

pending "Unrelated individuals" do
family_tree = {"Priya" => ["Rami"], "Kaito" => ["Elif"]}
relative_distance = RelativeDistance.new(family_tree)
relative_distance.degree_of_separation?("Priya", "Kaito").should eq(nil)
end

pending "Complex graph, cousins" do
family_tree = {
"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"],
}
relative_distance = RelativeDistance.new(family_tree)
relative_distance.degree_of_separation?("Dimitri", "Fabio").should eq(9)
end

pending "Complex graph, no shortcut, far removed nephew" do
family_tree = {
"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"],
}
relative_distance = RelativeDistance.new(family_tree)
relative_distance.degree_of_separation?("Lucia", "Jun").should eq(14)
end

pending "Complex graph, some shortcuts, cross-down and cross-up, cousins several times removed, with unrelated family tree" do
family_tree = {
"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"],
}
relative_distance = RelativeDistance.new(family_tree)
relative_distance.degree_of_separation?("Wyatt", "Xia").should eq(12)
end
end
3 changes: 3 additions & 0 deletions exercises/practice/relative-distance/src/relative_distance.cr
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class RelativeDistance
# Write your code for the 'RelativeDistance' exercise in this file.
end
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