gistfile1.py

def successor((x,y),X,Y):
    return set([
        (0,y), # empty X
        (x,0), # empty Y
        (X,y), # fill X
        (x,Y), # fill Y
        (0,y+x) if x+y<=Y else (x-(Y-y), y+(Y-y)), # X->Y
        (x+y,0) if x+y<=X else (x+(X-x), y-(X-x)), # Y->X
        ]) - set([(x,y)]) # remove self

def pour_problem(goal,X,Y):
    
    start = (0,0)
    frontier = [[start]]
    explored = set([start])
    
    while frontier:
        path = frontier.pop(0)
        u = path[-1]
        for v in successor(u,X,Y):
            if v not in explored:
                explored.add(v)
                new_path = path + [v]
                if goal in v:
                    return new_path
                else:
                    frontier.append(new_path)
                    
    return []

for goal in range(1,10):
    print goal, pour_problem(goal,5,9)