Solution to Sub-task: best line break

// helper function to find length of the line
// input -> [String] eg. ['he', ' ', 'l', 'lo'] 
// Output -> [Number] eg. 6
/*
There is only one implicit space between two words. There is no implicit
space between a word and an explicit space character or two explicit space
characters. The function caters to that length.
*/
function lineLength(line){
  if(line.length === 0) return 0;
  if(line.length === 1) return line[0].length;
  if(line[0] === ' '){
    return 1 + lineLength(line.slice(1));
  }
  else{
    return 1 + line[0].length + lineLength(line.slice(1));
  }
}
function bestLineBreak(lineCostFunc, dict, width, line){
  // split into possible lines
  let possibleLines = lineBreaks(dict, width, line);
  // add spaces
  possibleLines = possibleLines
    .map(x => {
      // add blanks
      let insertedBlanks = blankInsertions(width - lineLength(x[0]), x[0])
        .map(y => [y, x[1]])
      return insertedBlanks;
    })
    .reduce((prev, curr)=> prev.concat(curr), []); // flatten the array
  // filter maximum length lines:
  let maxLength = possibleLines.reduce((max, curr)=>{
    return max > lineLength(curr[0]) ? max : lineLength(curr[0]);
  },lineLength(possibleLines[0][0]))
  // filter all lines of maxLength
  possibleLines = possibleLines.filter(x => lineLength(x[0]) === maxLength);
  
  let minimumCostLine = possibleLines.reduce((min, curr)=>{
    return lineCostFunc(min[0]) > lineCostFunc(curr[0]) ? curr : min;
  }, possibleLines[0]);
  return minimumCostLine;
}
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(bestLineBreak (lineCost, enHyp, 15, ["He", "who", "controls"]))