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WS1920/hw5-setup.txt

+% Map Coloring
+
+% Original problem: https://www.tjhsst.edu/~rlatimer/assignments2004/colors.txt
+
+% It's known that only 4 colors are needed to paint any map so that no two neighboring states have the same color.
+% Write a Prolog program that receives a map and a list of 4 colors and  produces a colored map.
+% The map is represented by a list of states, each of which is a state name and a list of neighboring states.
+% For example, the maps of Australia and Western Europe are represented by the following maps.
+
+
+% Maps of Australia and West Europe, colors, define getcolor
+
+map('Australia',
+	[wa: [nt,sa], nt: [wa,sa,qld], qld:[nt,sa,nsw],
+	nsw: [qld,sa,vic], vic: [sa,nsw], tas:[], 
+	sa: [wa,nt,qld,nsw,vic]]).
+
+map('West Europe',
+	[portugal: [spain],
+	 spain: [portugal, france],
+	 belgium: [france, holland, luxembrg, germany],
+	 holland: [belgium, germany],
+	 luxembrg: [france, belgium, germany],
+	 switzerld: [france,germany,austria, italy],
+	 italy: [france,switzerld, austria],
+	 austria: [germany, switzerld, italy],
+	 france: [spain,belgium,luxembrg, germany,switzerld, italy],
+	 germany:[holland,belgium,luxembrg,france,switzerld, austria]]).
+
+colors([red,green,blue,yellow]).
+
+
+% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+% Edit section
+
+arrangecolors([],_,ColoredMap,ColoredMap).
+%	Tracing:
+%   :- write('Colormap='), write(ColoredMap),nl.
+arrangecolors([Country:Neighbors|Rest], ColorList, TempList, ColoredMap) :-
+	member(Color,ColorList),
+%	Tracing:
+%	write('Color:'), write(Color),write(' TempList:'), write(TempList),nl,
+	different(Color,Neighbors,TempList)
+	arrangecolors(Rest,ColorList,[Country:Color|TempList], ColoredMap).
+
+% TempList is in the format [country1:color1,country2:color2,...]
+restrictedness(Neighbors,TempList,R) :-
+    length(Neighbors,1),
+    length(TempList,1),
+    R = 1.
+
+
+% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+% Maybe useful things
+
+findneighbors(X, Map, Who) :-
+	map(Map, Countries),
+	neighbors(X,Countries,Who).
+
+neighbors(_,[],[]).
+neighbors(X,[X:Neighbors|_], Neighbors) :- !.  % Try this without the !
+neighbors(X,[_|RestofCountries], Neighbors) :-
+	neighbors(X,RestofCountries, Neighbors).
+
+adjacent(X,Y,Map) :-
+	findneighbors(X, Map, Countries),
+	member(Y, Countries).
+
+
+% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+% This you will most likely use
+
+different(C, Nbs, [S1:C1|Rest]) :-
+	not((member(S1,Nbs), C = C1)),
+	different(C, Nbs,Rest).
+different(_,_,[]).
+
+availablecolors(_,[],Colors,Colors).
+availablecolors(Neighbors,[NB:Color|TempListTail],TempColors,Colors) :- 
+    member(NB,Neighbors) ->
+    	availablecolors(Neighbors,TempListTail,[Color|TempColors],Colors);
+	    availablecolors(Neighbors,TempListTail,TempColors,Colors).
+
+countrieswithconstraints([],_,L,L).
+countrieswithconstraints([Country:Neighbors|Rest],TempList,Accumulator,CountriesWithConstraints) :-
+    countrieswithconstraints(Rest,TempList,[R-(Country:Neighbors)|Accumulator],CountriesWithConstraints),
+    restrictedness(Neighbors,TempList,R).
+
+sortedcountries(Countries,TempList,SortedCountries) :-
+    countrieswithconstraints(Countries,TempList,[],CountriesWithConstraints),
+    keysort(CountriesWithConstraints,SortedCountries).
+
+
+% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+% Main
+paint(Map,ColoredMap) :-
+	map(Map, Countries),
+	colors(ColorList),
+%	Tracing:
+%	write('ColoredMap is '), write(ColoredMap), nl.  
+	arrangecolors(Countries,ColorList,[], ColoredMap).
+
+% paint('Australia',ColoredMap).
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