Scala 怎么做如下变换：(A,B,C) => (A,(B,C)) (B,(A,C)) (C,(A,B))

[11]

(A,B,C) => (A,(B,C)) 这一步好说，直接取 head tail 就可以了。但是取每一个元素都做这个操作怎么搞？

[nil3]

scala> val a = Set(1, 2, 3)
a: scala.collection.immutable.Set[Int] = Set(1, 2, 3)

scala> a map (x => Set(x, a diff Set(x)))
res: scala.collection.immutable.Set[scala.collection.immutable.Set[Any]] = Set(Set(1, Set(2, 3)), Set(2, Set(1, 3)), Set(3, Set(1, 2)))

或者

scala> for (x <- a) yield Set(x, a diff Set(x))
res: scala.collection.immutable.Set[scala.collection.immutable.Set[Any]] = Set(Set(1, Set(2, 3)), Set(2, Set(1, 3)), Set(3, Set(1, 2)))