zebra-puzzle: add exercise (#197)

config.json

@@ -220,13 +220,21 @@
           "parsing"
         ]
       },
+      {
+        "slug": "zebra-puzzle",
+        "name": "Zebra Puzzle",
+        "uuid": "7b7a02a8-8a52-496d-8d04-60558545d4f7",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 1        
+      },
       {
         "slug": "collatz-conjecture",
         "name": "Collatz Conjecture",
         "uuid": "e6cebdbb-5b5c-4d87-a3f0-b8ec6d2438bf",
         "practices": [],
         "prerequisites": [],
-        "difficulty": 1        
+        "difficulty": 1
       }
     ]
   },

exercises/practice/zebra-puzzle/.docs/instructions.md

@@ -0,0 +1,24 @@
+# Instructions
+
+Solve the zebra puzzle.
+
+1. There are five houses.
+2. The Englishman lives in the red house.
+3. The Spaniard owns the dog.
+4. Coffee is drunk in the green house.
+5. The Ukrainian drinks tea.
+6. The green house is immediately to the right of the ivory house.
+7. The Old Gold smoker owns snails.
+8. Kools are smoked in the yellow house.
+9. Milk is drunk in the middle house.
+10. The Norwegian lives in the first house.
+11. The man who smokes Chesterfields lives in the house next to the man with the fox.
+12. Kools are smoked in the house next to the house where the horse is kept.
+13. The Lucky Strike smoker drinks orange juice.
+14. The Japanese smokes Parliaments.
+15. The Norwegian lives next to the blue house.
+
+Each of the five houses is painted a different color, and their inhabitants are of different national extractions, own different pets, drink different beverages and smoke different brands of cigarettes.
+
+Which of the residents drinks water?
+Who owns the zebra?

exercises/practice/zebra-puzzle/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "zebra_puzzle.pl"
+    ],
+    "test": [
+      "zebra_puzzle_tests.plt"
+    ],
+    "example": [
+      ".meta/zebra_puzzle.example.pl"
+    ]
+  },
+  "blurb": "Solve the zebra puzzle.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Zebra_Puzzle"
+}

exercises/practice/zebra-puzzle/.meta/tests.toml

@@ -0,0 +1,16 @@
+# 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.
+
+[16efb4e4-8ad7-4d5e-ba96-e5537b66fd42]
+description = "resident who drinks water"
+
+[084d5b8b-24e2-40e6-b008-c800da8cd257]
+description = "resident who owns zebra"

exercises/practice/zebra-puzzle/.meta/zebra_puzzle.example.pl

@@ -0,0 +1,33 @@
+zebra_owner(Owner) :-
+	houses(Hs),
+	member(h(Owner,zebra,_,_,_), Hs),
+    !.
+
+water_drinker(Drinker) :-
+	houses(Hs),
+	member(h(Drinker,_,_,water,_), Hs),
+    !.
+
+houses(Hs) :-
+	% each house in the list Hs of houses is represented as:
+	%      h(Nationality, Pet, Cigarette, Drink, Color)
+	length(Hs, 5),                                            %  1
+	member(h(english,_,_,_,red), Hs),                         %  2
+	member(h(spanish,dog,_,_,_), Hs),                         %  3
+	member(h(_,_,_,coffee,green), Hs),                        %  4
+	member(h(ukrainian,_,_,tea,_), Hs),                       %  5
+	next(h(_,_,_,_,green), h(_,_,_,_,white), Hs),             %  6
+	member(h(_,snake,winston,_,_), Hs),                       %  7
+	member(h(_,_,kool,_,yellow), Hs),                         %  8
+	Hs = [_,_,h(_,_,_,milk,_),_,_],                           %  9
+	Hs = [h(norwegian,_,_,_,_)|_],                            % 10
+	next(h(_,fox,_,_,_), h(_,_,chesterfield,_,_), Hs),        % 11
+	next(h(_,_,kool,_,_), h(_,horse,_,_,_), Hs),              % 12
+	member(h(_,_,lucky,juice,_), Hs),                         % 13
+	member(h(japanese,_,kent,_,_), Hs),                       % 14
+	next(h(norwegian,_,_,_,_), h(_,_,_,_,blue), Hs),          % 15
+	member(h(_,_,_,water,_), Hs),		% one of them drinks water
+	member(h(_,zebra,_,_,_), Hs).		% one of them owns a zebra
+
+next(A, B, Ls) :- append(_, [A,B|_], Ls).
+next(A, B, Ls) :- append(_, [B,A|_], Ls).

exercises/practice/zebra-puzzle/zebra_puzzle.pl

@@ -0,0 +1,3 @@
+zebra_owner(Owner).
+
+water_drinker(Drinker).

exercises/practice/zebra-puzzle/zebra_puzzle_tests.plt

@@ -0,0 +1,15 @@
+pending :-
+    current_prolog_flag(argv, ['--all'|_]).
+pending :-
+    write('\nA TEST IS PENDING!\n'),
+    fail.
+
+:- begin_tests(zebra_puzzle).
+
+    test(resident_who_drinks_water, condition(true)) :-
+        water_drinker(Resident), Resident == norwegian.
+
+    test(resident_who_owns_zebra, condition(true)) :-
+        zebra_owner(Resident), Resident == japanese.
+
+:- end_tests(zebra_puzzle).