For an array B, while it has more than one element, you can apply an operation on it - you choose any two elements x,y (they may be the same value, but they should have different indices), delete them, and add an element g(x,y) instead. code example

Example: create a function that checks the values of the indexes in two arrays and keep a score

const triplets = (arr1,arr2) => {
  let score1 = 0;
  let score2 = 0;
  let resultArr = [0,0]
  for (let i = 0; i < arr1.length; i++){
    if(arr1[i] === arr2[i]) {
      resultArr[0] = score1
      resultArr[1] = score2
    } else if (arr1[i] > arr2[i]) {
      score1++
      resultArr[0] = score1
    } else if (arr1[i] < arr2[i]) {
      score2++
      resultArr[1] = score2
    }
  }
  return resultArr
}