CODEWITHSUNDEEP
arraysscalasetcombinations
Cassie
Cassie

Reputation: 3099

Permutations with predicate Scala

I am trying to solve combinations task in Scala. I have an array with repeated elements and I have to count the number of combinations which satisfy the condition a+b+c = 0. Numbers should not be repeated, if they are in different places it doesn`t count as a distinct combination. So I turned my array into Set, so the elements would not repeat each other. Also, I have found about combinations method for sequences, but I am not really sure how to use it in this case. Also, I do not know where t put these permutations condition. Here is what I have for now:

var arr = Array(-1, -1, -2, -2, 1, -5, 1, 0, 1, 14, -8, 4, 5, -11, 13, 5, 7, -10, -4, 3, -6, 8, 6, 2, -9, -1, -4, 0)
val arrSet = Set(arr)
arrSet.toSeq.combinations(n)

I am new to Scala, so I would be really grateful for any advice!

Upvotes: 0

Views: 259

Answers (1)

lambdista
lambdista

Reputation: 1905

Here's what you need:

arr.distinct.combinations(3).filter(_.sum == 0).size

where:

  • distinct removes the duplicates
  • combinations(n) produces combinations of n elements
  • filter filters them by keeping only those whose sum is 0
  • size returns the total number of such combinations

P.S.: arr don't need to be a var. You should strive to never use var in Scala and stick to val as long as it's possible.

Upvotes: 3

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