
%   File   : MANDC
%   Author : Paul
%   Updated: 30 April 1985
%   Purpose: Missionaries and Cannibals by Lawrence Byrd

gofrom([0,0,0],[3,3,1],Oldlefts).

gofrom(Left,Right,Oldlefts):-
	legal(Left),
	legal(Right),
        not looping(Left,Oldlefts),
	applymove(Left,Right,Newleft,Newright),
	append([Left],Oldlefts,Newoldlefts),
	gofrom(Newleft,Newright,Newoldlefts).


applymove(Left,Right,Newleft,Newright):-
	boathere(Left),
	moveload(Left,Right,Newleft,Newright).

applymove(Left,Right,Newleft,Newright):-
	boathere(Right),
	moveload(Right,Left,Newright,Newleft).

boathere([Missionaries,Cannibals,1]).

moveload(Source,Target,Newsource,Newtarget):-
	move(Boatload),
	possibletomove(Source,Boatload),
	performthemove(Source,Target,Boatload,Newsource,Newtarget).


possibletomove([M,C,B],[MoveM,MoveC,MoveB]):-
	M>=MoveM,
	C>=MoveC,
	B>=MoveB.

performthemove([SourceM,SourceC,SourceB],
	       [TargetM,TargetC,TargetB],
	       [MoveM,MoveC,MoveB],
	       [NewsourceM,NewsourceC,NewsourceB],
	       [NewtargetM,NewtargetC,NewtargetB]):-
	NewsourceM is SourceM-MoveM,
	NewsourceC is SourceC-MoveC,
	NewsourceB is SourceB-MoveB,
	NewtargetM is TargetM+MoveM,
	NewtargetC is TargetC+MoveC,
	NewtargetB is TargetB+MoveB.


member(X,[X|_]).
member(X,[Y|Z]):-member(X,Z).

append([],L,L).
append([H|L1],L2,[H|L3]):-append(L1,L2,L3).


     