gistfile1.py

def check_route(board, route):
    w = board.w
    h = board.h
    state = bytearray(board.state)
    pos = board.state.index(b'0')

    try:
        for c in route:
            if c == 'D':
                npos = pos+w
                if npos >= w*h:
                    return False
            elif c == 'U':
                npos = pos-w
                if npos < 0:
                    return False
            elif c == 'L':
                if pos%w == 0:
                    return False
                npos = pos-1
            elif c == 'R':
                if (pos+1)%w == 0:
                    return False
                npos = pos+1
            else:
                return False
            if state[npos] == b'=' or state[pos] == b'=':
                return False
            state[pos], state[npos] = state[npos], state[pos]
            pos = npos
    except IndexError:
        return False

    expected = make_goal(board.state)
    result = bytes(state)
    return expected == result

PLATES = '123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ0'

def make_goal(state):
    N = len(state)
    state = bytearray(state)
    for i in xrange(N):
        if state[i] != ord('='):
            state[i] = PLATES[i]
    state[-1] = '0'
    return bytes(state)