% nacteni:
/* ['2.3_5.pl']. */
del1(A,[A|T],T).
del1(A,[H|T1],[H|T2]) :- del1(A,T1,T2).
insert(A,L,[A|L]).
insert(A,[H|T1],[H|T2]):- insert(A,T1,T2).
perm1([],[]).
perm1([H|T],L):- perm1(T,V), insert(H,V,L).
perm2([],[]).
perm2(L,[X|P]) :- del1(X,L,L1),perm2(L1,P).
perm3([],[]).
perm3(L,[H|T]):- append(A,[H|B],L),append(A,B,L1), perm3(L1,T).
% demonstracni vypis
% abychom se vyhli varovanim "Redefined static procedure ..."
:- dynamic
write_all_X/3,
start/0.
write_all_X(Goal,X,Name):-
call(Goal),write(' '),write(Name),write(' = '),write(X),nl,fail.
write_all_X(_,_,_).
start:-
write('Prace se seznamy - permutace'),nl,
write('-------------------------------'),nl,
write('perm1 napsany pomoci insert, vysledek volani "perm1([1,2,3],L)" :'),
nl, write_all_X(perm1([1,2,3],L), L, 'L'),nl,
write('Pro blizsi porozumneni si vyzkousejte perm1, perm2 (reseny '), nl,
write('pomoci del1) a perm3 (s append) s trasovanim, napr. takto:'), nl,
write('trace, perm1([1,2,3],L).'),nl,
write('Pozn.: Po vypsani prvniho vysledku si dalsi vyzadate stisnutim ";"').
?-start.
:- retractall(write_all_X/3).
:- retractall(start/0).
Prace se seznamy - permutace
-------------------------------
perm1 napsany pomoci insert, vysledek volani "perm1([1,2,3],L)" :
L = [1,2,3]
L = [2,1,3]
L = [2,3,1]
L = [1,3,2]
L = [3,1,2]
L = [3,2,1]
Pro blizsi porozumneni si vyzkousejte perm1, perm2 (reseny
pomoci del1) a perm3 (s append) s trasovanim, napr. takto:
trace, perm1([1,2,3],L).
Pozn.: Po vypsani prvniho vysledku si dalsi vyzadate stisnutim ";"
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