CODEWITHSUNDEEP
scala
Dmitrii
Dmitrii

Reputation: 624

Multiply elements of list of lists with each other

I have List of lists List[List[Int] to n] and Lists[Int] are of different size and i want to multiply values all of them between each other. For List(List(1,2,3), List(4,5), List(6)) it would be

1*4*6, 1*5*6, 2*4*6, 2*5*6, 3*4*6, 3*5*6

and so on and return result as a List of resulting values List[24, 30, 48, 60, 72, 90]

Upvotes: 1

Views: 1915

Answers (1)

Nyavro
Nyavro

Reputation: 8866

You can do it using foldLeft this way: 

list.foldLeft(List(1)) {
  case (acc, item) => acc.flatMap(v => item.map(_*v))
}

Explanation

Lets define method producing all possible multiplication of pairs of two lists:

def mul(a:List[Int], b:List[Int]) = b.flatMap (item => a.map(_*item))

this method for each item in b produces a list of items from a multiplied by current value of b

Now we can apply this procedure to all elements of list of lists, giving it initial value of List(1)

Upvotes: 4

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