JavaScript

Exercises Set 12

const rangeSum = arr => {
  // your code here
}

// Refer: https://stackoverflow.com/a/20066663

const rangeSum = arr => {
  const sortedArray = [...arr].sort((a, b) => a - b);
  const start = sortedArray[0];
  const end = sortedArray[1];
  const iterations = end - start + 1;
  return Array.apply(null, { length: iterations })
    .map(Number.call, Number)
    .map(num => num + start)
    .reduce((sum, currentValue) => sum + currentValue, 0);
};