Solution to Sub-task: Line Cost

// helper function to find blank positions relative one another
// input -> [String] Number eg. ['he', ' ', 'l', 'lo'] 0
// Output -> [Number] 
// eg. [1, 2] 
/*
Each number is the distance of a space character from either the start of the 
line or the preceding space character. The last number is the distance of the
end of line from either the start of the line or the preceding space character.
*/
function blankPlacements(line, position){
  if(line.length === 0) return [position];
  let [head, ...rest] = line;
  if(head === ' '){
    return [position, ...blankPlacements(rest, 0)];
  }
  else{
    return blankPlacements(rest, position +1);
  }
}
function lineCost(line){
  // get blank positions
  let blankPositions = blankPlacements(line, 0);
  // get sum of blank positions
  let sum = blankPositions.reduce((prev,acc)=> prev + acc ,0);
  // get average of the positions
  let average = sum / blankPositions.length
  // calculate variance below
  let sumOfSquaredDiff = blankPositions
    .map(x => (x - average)**2) // squared differences from the mean
    .reduce((prev,curr) => prev + curr, 0) // sum of differences 
  let variance = sumOfSquaredDiff / blankPositions.length;
  
  // count hyphens
  let hyphenCount = line
    .map(x => x.match(/[-]/g) ? 1 : 0) // check for hyphens
    .reduce((prev,acc)=> prev + acc ,0); // count hyphens
  // count additional blanks
  let numberOfBlanks = line
    .map(x => x === ' ' ? 1 : 0) // check for blanks
    .reduce((prev,acc)=> prev + acc ,0); // count blanks
  
  let totalCost = blankCost * numberOfBlanks
    + blankProxCost * (line.length - average)
    + blankUnevenCost * variance
    + hypCost * hyphenCount;
  
  return totalCost;
}
enHyp = {
  "creative" : ["cr","ea","ti","ve"], 
  "controls" : ["co","nt","ro","ls"], 
  "achieve" : ["ach","ie","ve"], 
  "future" : ["fu","tu","re"], 
  "present" : ["pre","se","nt"], 
  "motivated" : ["mot","iv","at","ed"], 
  "desire" : ["de","si","re"], 
  "others" : ["ot","he","rs"],
}
const blankCost = 1.0
const blankProxCost = 1.0
const blankUnevenCost = 1.0
const hypCost = 1.0
console.log(lineCost (["He", " ", " ", "who", "cont-"]));
console.log(lineCost (["He", " ", "who", " ", "cont-"]));