Add queen-attack

config.json

@@ -262,6 +262,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "queen-attack",
+        "name": "Queen Attack",
+        "uuid": "42c10a4c-140f-40d0-9a46-8373dd7d7a72",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "rna-transcription",
         "name": "RNA Transcription",

exercises/practice/queen-attack/.docs/instructions.md

@@ -0,0 +1,21 @@
+# Instructions
+
+Given the position of two queens on a chess board, indicate whether or not they are positioned so that they can attack each other.
+
+In the game of chess, a queen can attack pieces which are on the same row, column, or diagonal.
+
+A chessboard can be represented by an 8 by 8 array.
+
+So if you are told the white queen is at `c5` (zero-indexed at column 2, row 3) and the black queen at `f2` (zero-indexed at column 5, row 6), then you know that the set-up is like so:
+
+![A chess board with two queens. Arrows emanating from the queen at c5 indicate possible directions of capture along file, rank and diagonal.](https://assets.exercism.org/images/exercises/queen-attack/queen-capture.svg)
+
+You are also able to answer whether the queens can attack each other.
+In this case, that answer would be yes, they can, because both pieces share a diagonal.
+
+## Credit
+
+The chessboard image was made by [habere-et-dispertire][habere-et-dispertire] using LaTeX and the [chessboard package][chessboard-package] by Ulrike Fischer.
+
+[habere-et-dispertire]: https://exercism.org/profiles/habere-et-dispertire
+[chessboard-package]: https://github.com/u-fischer/chessboard

exercises/practice/queen-attack/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "queen-attack.rkt"
+    ],
+    "test": [
+      "queen-attack-test.rkt"
+    ],
+    "example": [
+      ".meta/example.rkt"
+    ]
+  },
+  "blurb": "Given the position of two queens on a chess board, indicate whether or not they are positioned so that they can attack each other.",
+  "source": "J Dalbey's Programming Practice problems",
+  "source_url": "https://users.csc.calpoly.edu/~jdalbey/103/Projects/ProgrammingPractice.html"
+}

exercises/practice/queen-attack/.meta/example.rkt

@@ -0,0 +1,27 @@
+#lang racket
+
+(provide create-queen
+         can-attack?)
+
+(struct queen (row column))
+
+(define (grid-position? n)
+  (and (exact-nonnegative-integer? n)
+       (> 8 n)))
+
+(define/contract (create-queen row column)
+  (-> grid-position? grid-position? queen?)
+  (queen row column))
+
+(define/contract (can-attack? white-queen black-queen)
+  (-> queen? queen? boolean?)
+  (match (list white-queen black-queen)
+    [(list (queen r _) (queen r _))
+     #t]
+    [(list (queen _ c) (queen _ c))
+     #t]
+    [(list (queen wr wc) (queen br bc))
+     #:when (= (abs (- wr br))
+               (abs (- wc bc)))
+     #t]
+    [_ #f]))

exercises/practice/queen-attack/.meta/tests.toml

@@ -0,0 +1,49 @@
+# 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.
+
+[3ac4f735-d36c-44c4-a3e2-316f79704203]
+description = "Test creation of Queens with valid and invalid positions -> queen with a valid position"
+
+[4e812d5d-b974-4e38-9a6b-8e0492bfa7be]
+description = "Test creation of Queens with valid and invalid positions -> queen must have positive row"
+
+[f07b7536-b66b-4f08-beb9-4d70d891d5c8]
+description = "Test creation of Queens with valid and invalid positions -> queen must have row on board"
+
+[15a10794-36d9-4907-ae6b-e5a0d4c54ebe]
+description = "Test creation of Queens with valid and invalid positions -> queen must have positive column"
+
+[6907762d-0e8a-4c38-87fb-12f2f65f0ce4]
+description = "Test creation of Queens with valid and invalid positions -> queen must have column on board"
+
+[33ae4113-d237-42ee-bac1-e1e699c0c007]
+description = "Test the ability of one queen to attack another -> cannot attack"
+
+[eaa65540-ea7c-4152-8c21-003c7a68c914]
+description = "Test the ability of one queen to attack another -> can attack on same row"
+
+[bae6f609-2c0e-4154-af71-af82b7c31cea]
+description = "Test the ability of one queen to attack another -> can attack on same column"
+
+[0e1b4139-b90d-4562-bd58-dfa04f1746c7]
+description = "Test the ability of one queen to attack another -> can attack on first diagonal"
+
+[ff9b7ed4-e4b6-401b-8d16-bc894d6d3dcd]
+description = "Test the ability of one queen to attack another -> can attack on second diagonal"
+
+[0a71e605-6e28-4cc2-aa47-d20a2e71037a]
+description = "Test the ability of one queen to attack another -> can attack on third diagonal"
+
+[0790b588-ae73-4f1f-a968-dd0b34f45f86]
+description = "Test the ability of one queen to attack another -> can attack on fourth diagonal"
+
+[543f8fd4-2597-4aad-8d77-cbdab63619f8]
+description = "Test the ability of one queen to attack another -> cannot attack if falling diagonals are only the same when reflected across the longest falling diagonal"

exercises/practice/queen-attack/queen-attack-test.rkt

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+#lang racket/base
+
+(require "queen-attack.rkt")
+
+(module+ test
+  (require rackunit rackunit/text-ui)
+
+  (define suite
+    (test-suite
+     "queen-attack tests"
+
+     (test-not-exn "queen with a valid position"
+                   (lambda () (create-queen 2 2)))
+
+     (test-exn "queen must have positive row"
+                exn:fail?
+                (lambda () (create-queen -2 2)))
+
+     (test-exn "queen must have row on board"
+                exn:fail?
+                (lambda () (create-queen 8 4)))
+
+     (test-exn "queen must have positive column"
+                exn:fail?
+                (lambda () (create-queen 2 -2)))
+
+     (test-exn "queen must have column on board"
+                exn:fail?
+                (lambda () (create-queen 4 8)))
+
+     (test-false "cannot attack"
+                 (can-attack? (create-queen 2 4)
+                              (create-queen 6 6)))
+
+    (test-true "can attack on same row"
+               (can-attack? (create-queen 2 4)
+                            (create-queen 2 6)))
+
+    (test-true "can attack on same column"
+               (can-attack? (create-queen 4 5)
+                            (create-queen 2 5)))
+
+    (test-true "can attack on first diagonal"
+               (can-attack? (create-queen 2 2)
+                            (create-queen 0 4)))
+
+    (test-true "can attack on second diagonal"
+               (can-attack? (create-queen 2 2)
+                            (create-queen 3 1)))
+
+    (test-true "can attack on third diagonal"
+               (can-attack? (create-queen 2 2)
+                            (create-queen 1 1)))
+
+    (test-true "can attack on fourth diagonal"
+               (can-attack? (create-queen 1 7)
+                            (create-queen 0 6)))
+
+    (test-false "cannot attack if falling diagonals are only the same when reflected across the longest falling diagonal"
+                (can-attack? (create-queen 4 1)
+                             (create-queen 2 5)))))
+
+  (run-tests suite))
+

exercises/practice/queen-attack/queen-attack.rkt

@@ -0,0 +1,10 @@
+#lang racket
+
+(provide create-queen
+         can-attack?)
+
+(define (create-queen row column)
+  (error "Not implemented yet"))
+
+(define (can-attack? white-queen black-queen)
+  (error "Not implemented yet"))