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pl:prolog:pllib:map_colouring2 [2019/06/27 15:50] (aktualna)
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 +====== Map colouring2 ======
 +{{tag>​map problem_solving}}
 +===== Description =====
 +Map coloring
 +
 +{{:​prolog:​pllib:​map_colouring2.png|}}
 +
 +**Source**: ​ "The Art of Prolo
 +
 +
 +===== Download =====
 +Program source code: {{map_colouring2.pl}}
 +===== Listing =====
 +<code prolog>
 +/*
 +
 +color_map(Map,​Colors) :-
 +
 + Map is colored with Colors, so that no two neighbors have the same
 +
 + color. The map is represented as an adjacency-list of regions
 +
 + region(Name,​Color,​Neighbors),​ where Name is the name of the
 +
 + region, Color is its color, and Neighbors are the colors of the 
 +
 + neighbors. ​
 +
 +*/
 +
 + color_map([Region|Regions],​Colors) :-
 +
 + color_region(Region,​Colors),​
 +
 + color_map(Regions,​Colors).
 +
 + color_map([],​Colors).
 +
 +/*
 +
 +   ​color_region(Region,​Colors) :-
 +
 + Region and its neighbors are colored using Colors so that the
 +
 + region'​s color is different from the color of any of its neighbors.
 +
 +*/
 +
 + color_region(region(Name,​Color,​Neighbors),​Colors) :-
 +
 + select(Color,​Colors,​Colors1),​
 +
 + members(Neighbors,​Colors1).
 +
 +
 +
 + select(X,​[X|Xs],​Xs).
 +
 + select(X,​[Y|Ys],​[Y|Zs]) :- select(X,​Ys,​Zs).
 +
 +
 +
 +     ​members([X|Xs],​Ys) :- member(X,​Ys),​ members(Xs,​Ys).
 +
 +     ​members([],​Ys).
 +
 +
 +
 + /* Test data */
 +
 +
 +
 + test_color(Name,​Map) :-
 +
 + map(Name,​Map),​
 +
 + colors(Name,​Colors),​
 +
 + color_map(Map,​Colors).
 +
 +
 +
 + map(test,​[region(a,​A,​[B,​C,​D]), ​    ​region(b,​B,​[A,​C,​E]), ​
 +
 +       region(c,​C,​[A,​B,​D,​E,​F]),​ region(d,​D,​[A,​C,​F]),​
 +
 +   region(e,​E,​[B,​C,​F]), ​    ​region(f,​F,​[C,​D,​E])]).
 +
 +
 +
 + map(west_europe,​
 +
 + [ region(portugal,​P,​[E]), ​ region(spain,​E,​[F,​P]),​
 +
 + region(france,​F,​[E,​I,​S,​B,​WG,​L]), ​ region(belgium,​B,​[F,​H,​L,​WG]),​
 +
 + region(holland,​H,​[B,​WG]),​ region(west_germany,​WG,​[F,​A,​S,​H,​B,​L]),​
 +
 + region(luxembourg,​L,​[F,​B,​WG]),​ region(italy,​I,​[F,​A,​S]),​
 +
 + region(switzerland,​S,​[F,​I,​A,​WG]),​ region(austria,​A,​[I,​S,​WG])]).
 +
 +
 +
 + colors(X,​[red,​yellow,​blue,​white]).
 +
 +
 +
 +
 +
 +% Program 14.4: Map coloring
 +
 +%?- test_color(west_europe,​X).
 +
 +
 +
 +</​code>​
 +===== Comments =====
  
pl/prolog/pllib/map_colouring2.txt · ostatnio zmienione: 2019/06/27 15:50 (edycja zewnętrzna)
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