#Python, 1761

Kind of burnt out on this question, so couldn't bring myself to golf it. Either way, right now it's the only solution that solves everything within the time limit (longest, #3, takes 27 seconds).

pieces = {}
taken = set()
goals = set()

y = 0
while True:
    try:
        for x, c in enumerate(input()):
            if c == ".": continue
            if c == "g":
                goals.add((x, y))
            else:
                if c in "0123456789":
                    if c not in pieces: pieces[c] = set()
                    pieces[c].add((x, y))
                taken.add((x, y))

        y += 1

    except: break

def translate_comp(coords):
    o = min(sorted(coords))
    return set((c[0] - o[0], c[1] - o[1]) for c in coords)

similar = {}
for piece in pieces:
    k = tuple(translate_comp(pieces[piece]))
    if k not in similar: similar[k] = []
    similar[k].append(piece)


seen = set()
states = [(pieces, taken, ())]
while states:
    state = states.pop(0)
    if not goals - state[0]["0"]:
        names = {
            (-1, 0): "L",
            (1, 0): "R",
            (0, 1): "D",
            (0, -1): "U",
        }

        print(len(state[2]))
        print(" ".join(piece + names[d] for d, piece in state[2]))
        break

    for piece in pieces:
        for d in ((-1, 0), (1, 0), (0, 1), (0, -1)):
            new_pieces = state[0].copy()
            new_pieces[piece] = {(c[0] + d[0], c[1] + d[1]) for c in state[0][piece]}
            new_taken = state[1] - state[0][piece]

            # Collision
            if new_pieces[piece] & new_taken:
                continue

            gist = tuple(frozenset().union(*(new_pieces[piece] for piece in similar_set))
                         for similar_set in similar.values())

            if gist in seen:
                continue

            seen.add(gist)
            new_taken |= new_pieces[piece]
            states.append((new_pieces, new_taken, state[2] + ((d, piece),)))