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15 changes: 15 additions & 0 deletions config.json
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Expand Up @@ -788,6 +788,21 @@
"difficulty": 3,
"status": "beta"
},
{
"slug": "relative-distance",
"name": "Relative Distance",
"uuid": "5e06855b-2894-4b30-992d-1a7af376d2ec",
"practices": [
"conditionals",
"hash-tables",
"mapping"
],
"prerequisites": [
"conditionals",
"hash-tables"
],
"difficulty": 5
},
{
"slug": "robot-name",
"name": "Robot Name",
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.

- 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 3 (Tariq → Helena → Isla → Uma).
There's no known relationship between Isla and [Kevin][six-bacons], 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]: 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": [
"BNAndras"
],
"files": {
"solution": [
"relative-distance.lisp"
],
"test": [
"relative-distance-test.lisp"
],
"example": [
".meta/example.lisp"
]
},
"blurb": "Given a family tree, calculate the degree of separation.",
"source": "vaeng",
"source_url": "https://github.com/exercism/problem-specifications/pull/2537"
}
54 changes: 54 additions & 0 deletions exercises/practice/relative-distance/.meta/example.lisp
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(defpackage :relative-distance
(:use :cl)
(:export :degree-of-separation))

(in-package :relative-distance)

(defun degree-of-separation (family-tree person-a person-b)
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I think factoring this out into a few functions might be good. for example the tree parsing could be its own function

(let ((neighbors (make-hash-table :test 'equal)))

(dolist (entry family-tree)
(let ((parent (car entry))
(children (cdr entry)))

(unless (gethash parent neighbors)
(setf (gethash parent neighbors) (make-hash-table :test 'equal)))

(dolist (child children)
(unless (gethash child neighbors)
(setf (gethash child neighbors) (make-hash-table :test 'equal)))
(setf (gethash child (gethash parent neighbors)) t)
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setf can take pairs of symbols and values so instead of (setf a b) (setf c d) you can do (setf a b c d). I personally think it looks nicer instead of two expressions.

(setf (gethash parent (gethash child neighbors)) t))

(dolist (child-a children)
(dolist (child-b children)
(unless (equal child-a child-b)
(setf (gethash child-a (gethash child-b neighbors)) t)
(setf (gethash child-b (gethash child-a neighbors)) t))))))

(unless (and (gethash person-a neighbors) (gethash person-b neighbors))
(return-from degree-of-separation nil))


(let ((queue (list (cons person-a 0)))
(visited (make-hash-table :test 'equal)))

(setf (gethash person-a visited) t)

(loop while queue do
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Starting to review the function I was thinking: "oh dolist not loop nice..." but now that I see loop I wonder why you didn't use loop above as well. You could do something like: (loop for (parent . child) in tree ...)

I don't care do vs. loop but think it would good to be consistent.

(let* ((current (pop queue))
(current-person (car current))
(current-degree (cdr current)))

(when (equal current-person person-b)
(return-from degree-of-separation current-degree))
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How about you factor this loop so it evaluates to current-degree and then this whole function can evaluate to what this loop evaluates to?


(let ((current-neighbors (gethash current-person neighbors)))
(when current-neighbors
(maphash (lambda (neighbor _)
(unless (gethash neighbor visited)
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Don't you get a STYLE-WARNING here about the unused symbol _? Use (declare (ignore _)) Maybe give it a reasonable name even though it is ignored...

(setf (gethash neighbor visited) t)
(setf queue (append queue (list (cons neighbor (1+ current-degree)))))))
current-neighbors))))))

nil))
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"
217 changes: 217 additions & 0 deletions exercises/practice/relative-distance/relative-distance-test.lisp
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;; Ensures that relative-distance.lisp and the testing library are always loaded
(eval-when (:compile-toplevel :load-toplevel :execute)
(load "relative-distance")
(quicklisp-client:quickload :fiveam))

;; Defines the testing package with symbols from relative-distance and FiveAM in scope
;; The `run-tests` function is exported for use by both the user and test-runner
(defpackage :relative-distance-test
(:use :cl :fiveam)
(:export :run-tests))

;; Enter the testing package
(in-package :relative-distance-test)

;; Define and enter a new FiveAM test-suite
(def-suite* relative-distance-suite)

(test direct-parent-child-relation
(let ((family-tree '(("Vera" . ("Tomoko"))
("Tomoko" . ("Aditi"))))
(person-a "Vera")
(person-b "Tomoko"))
(is (= 1 (relative-distance:degree-of-separation family-tree person-a person-b)))))

(test sibling-relationship
(let ((family-tree '(("Dalia" . ("Olga" "Yassin"))))
(person-a "Olga")
(person-b "Yassin"))
(is (= 1 (relative-distance:degree-of-separation family-tree person-a person-b)))))

(test two-degrees-of-separation-grandchild
(let ((family-tree '(("Khadija" . ("Mateo"))
("Mateo" . ("Rami"))))
(person-a "Khadija")
(person-b "Rami"))
(is (= 2 (relative-distance:degree-of-separation family-tree person-a person-b)))))

(test unrelated-individuals
(let ((family-tree '(("Priya" . ("Rami"))
("Kaito" . ("Elif"))))
(person-a "Priya")
(person-b "Kaito"))
(is (equal NIL (relative-distance:degree-of-separation family-tree person-a person-b)))))

(test complex-graph-cousins
(let ((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"))))
(person-a "Dimitri")
(person-b "Fabio"))
(is (= 9 (relative-distance:degree-of-separation family-tree person-a person-b)))))

(test complex-graph-no-shortcut-far-removed-nephew
(let ((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"))))
(person-a "Lucia")
(person-b "Jun"))
(is (= 14 (relative-distance:degree-of-separation family-tree person-a person-b)))))

(test complex-graph-some-shortcuts-cross-down-and-cross-up-cousins-several-times-removed-with-unrelated-family-tree
(let ((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"))))
(person-a "Wyatt")
(person-b "Xia"))
(is (= 12 (relative-distance:degree-of-separation family-tree person-a person-b)))))

(defun run-tests (&optional (test-or-suite 'relative-distance-suite))
"Provides human readable results of test run. Default to entire suite."
(run! test-or-suite))
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