% Swap the first with the third element from a list
swap_1_3([],[]).
swap_1_3([A],[A]):-!.
swap_1_3([A,B],[A,B]):-!.
swap_1_3([H1,H2,H3|T],[H3,H2,H1|T]).

% ?-swap_1_3([3,4,a,d,5],X).
% X=[a,4,3,d,5]
% ?-swap_1_3([3,4],X).
% X=[3,4]


%%%% min from a list
minlist([X],X):-!.
minlist([H1,H2|T],R):-H1 < H2,!, minlist([H1|T],R).
minlist([H1,H2|T],R):- H2 =< H1, minlist([H2|T],R).

%[2,3,4,1]        ?
%[2,   4,1]       ?

%%%%%%%%%%%%%%%%%%%
% L=[-1,-4,3,5,6,-10]
% L1=[-1,-4,-10]
% L2=[3,5]
% L3=[6]

split_list([],[],[],[]).
split_list([H|T],[H|R],Odd,Even):-H<0,!,split_list(T,R,Odd,Even).
split_list([H|T],R,[H|Odd],Even):- X is H mod 2, X=1,!, split_list(T,R,Odd,Even).
split_list([H|T],R,Odd,[H|Even]):- split_list(T,R,Odd,Even).

% ?-split_list([-10,-11,-23],L1,L2,L3).
% ?-split_list([2,3,-1,-10,-11,23,5,4,-1],X,Y,Z).

%%%%%%%%%%%%%% split_list with acc
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%split_list2(List,Neg,Odd,Even):-split_listAcc(List,[],Neg,[],Odd,[],Even).


split_list2(List,Neg,Odd,Even):-split_listAcc(List,[],Neg,[],Odd,[],Even).
split_listAcc([],Acc1,Acc1,Acc2,Acc2,Acc3,Acc3).
split_listAcc([H|T],Acc1,Neg,Acc2,Odd,Acc3,Even):-H<0,!, add_to_end(H,Acc1,NewAcc1), 
					split_listAcc(T,NewAcc1,Neg,Acc2,Odd,Acc3,Even).
split_listAcc([H|T],Acc1,Neg,Acc2,Odd,Acc3,Even):-H>=0, X is H mod 2, X=1, !, add_to_end(H,Acc2,NewAcc2),
					split_listAcc(T,Acc1,Neg,NewAcc2,Odd,Acc3,Even).
split_listAcc([H|T],Acc1,Neg,Acc2,Odd,Acc3,Even):-add_to_end(H,Acc3,NewAcc3),
					split_listAcc(T,Acc1,Neg,Acc2,Odd,NewAcc3,Even).

% ?-split_list2([-10,-11,-23],L1,L2,L3).
% ?-split_list2([2,3,-1,-10,-11,23,5,4,-1],X,Y,Z).


%%%%%%%%%%%%% count occurrences of an element in a list
% without accumulators
count_occ(_,[],0):-!.
count_occ(El,[El|T],N):-!,count_occ(El,T,N1), N is N1+1.
count_occ(El,[_|T],N):-count_occ(El,T,N).

% ?-count_occ(2,[3,2,4,5,2,3,2,2,2],X).
% ?-count_occ(2,[5,6,7,8],X).

% with acc
count_occ2(El,List,Res):-countacc(El,List,0,Res).
countacc(_,[],Acc,Acc):-!.
countacc(El,[El|T],Acc,Res):-NewAcc is Acc+1,!, countacc(El,T,NewAcc,Res).
countacc(El,[_|T],Acc,Res):-countacc(El,T,Acc,Res).

% ?-count_occ2(2,[3,2,4,5,2,3,2,2,2],X).
% ?-count_occ2(2,[5,6,7,8],X).