SOLVING WATER JUG PROBLEM

AIM:
 To write a prolog program to implement water jug problem.

ALGORITHM:
 STEP 1: Fill the 4 gallon jug if x<4.
 STEP 2: Fill the 3 gallon jug if x<3.
 STEP 3: Pour some water out of the 4 gallon jug (if x>0).
 STEP 4: Pour some water out of the 3 gallon jug (if x>0).
 STEP 5: Empty the 4 gallon jug on the ground (if x>0).
 STEP 6: Empty the 3 gallon jug on the ground (if y>0).
 STEP 7: Pour the water from the 3 gallon jug into the 4 gallon jug until the 4 gallon jug is full 
 (if x+y>=4 and y>0).
 STEP 8: Pour the water from the 4 gallon jug into the 3 gallon jug until the 3 gallon jug is full 
 (if x+y>=3 and x>0). 
 STEP 9: Pour all the water from 3 gallon jug into the 4 gallon jug (if x+y<=4 and y>0).
 STEP 10: Pour all the water from 4 gallon jug into the 3 gallon jug (if x+y<=3 and x>0).

PROGRAM:
 member(X,[X|_]).
 member(X,[Y|Z]):-member(X,Z).
 move(X,Y,_):-X=:=2,Y=:=0,write('done'),!.
 move(X,Y,Z):-X<4,\+member((4,Y),Z),write("fill 4 jug"),nl,move(4,Y,[(4,Y)|Z]).
 move(X,Y,Z):-Y<3,\+member((X,3),Z),write("fill 3 jug"),nl,move(X,3,[(X,3)|z]).
 move(X,Y,Z):-X>0,\+member((0,Y),Z),write("pour 4 jug"),nl,move(0,Y,[(0,Y)|Z]).
 move(X,Y,Z):-Y>0,\+member((X,0),Z),write("pour 3 jug"),nl,move(X,0,[(X,0)|Z]).
 move(X,Y,Z):-P is X+Y,P>=4,Y>0,K is 4-X,M is Y-K,\+member((4,M),Z),write("pour from 
 3jug to 4jug"),nl,move(4,M,[(4,M)|Z]).
 move(X,Y,Z):-P is X+Y,P>=3,X>0,K is 3-Y,M is X-K,\+member((M,3),Z),write("pour from 
 4jug to 3jug"),nl,move(M,3,[(M,3)|Z]).
 move(X,Y,Z):-K is X+Y,K<4,Y>0,\+member((K,0),Z),write("pour from 3jug to 
 4jug"),nl,move(K,0,[(K,0)|Z]).
 move(X,Y,Z):-K is X+Y,K<3,X>0,\+member((0,K),Z),write("pour from 4jug to 
 3jug"),nl,move(0,K,[(0,K)|Z]).

OUTPUT:
 ?- move(0,0,[(0,0)])
 fill 4 jug
 fill 3 jug
 pour 4 jug
 pour 3 jug
 fill 4 jug
 pour from 4jug to 3jug
 pour 3 jug
 pour from 4jug to 3jug
 fill 4 jug
 pour from 4jug to 3jug
 pour 3 jug
 done

RESULT:
 Thus the program to implement water jug problem using prolog was executed and the 
 output was verified successfully.