每个点的入度是多少

六门课的先修关系：0→2、1→2、2→3、2→4、3→5、4→5。运行下面这段程序：

def indeg(g):
    d = {u: 0 for u in g}
    for u in g:
        for v in g[u]:
            d[v] += 1
    return [d[i] for i in sorted(g)]

print("/".join(str(x) for x in indeg({0: [2], 1: [2], 2: [3, 4], 3: [5], 4: [5], 5: []})))