如何在其他Python字典中分发JSON文件中特定“key”的“key”元素？

Question

td1 ={}
td2 = {}
td3 = {}
td4 = {}

test.json

{
"a1":"a11",
"b1":"b11",
"c1":"c11",
"sub1":
    {
      "d1":"d11",
      "e1":"e11",
      "f1":"f11",
      ......
      ......
      ......
      "f10":"f100"
    },
"sub2":
    {
      "g1":"g11",
      "h1":"h11",
      "i1":"i11",
      ......
      ......
      ......
      "j10":"j100"
    }
}

输出应为：

td1 = {"d1":"sub1","g1":"sub2","f20":"sub1"}
td2 = {"e1":"sub1","h1":"sub2","d20":"sub1"}
td3 = {"e10":"sub1","h12":"sub2","d15":"sub1"}
td4 = {"f10":"sub1","j10":"sub2","f12":"sub1"}

sub1的JSON内容的所有元素&sub2，应平均分布在4个词典中（td1,td2,td3,td4） 比如说，如果sub1有12个元素，那么每个字典将分配3个元素。 如果存在2个、3个、5个、13个或14个元素，则应相应地进行分配。 与sub2类似

No duplication。如果d1已分配给td1,，则无法分配给任何其他词典

如何做到这一点By grouping？或任何其他机制，如round-robin或unique元素概念