Drill 19: Rewrite it — Complexity and Big O

// O(n): one pass
function total(values) {
  let sum = 0
  for (const value of values) sum += value
  return sum
}

// O(n^2): compare every pair
function hasDuplicate(values) {
  for (let i = 0; i < values.length; i++)
    for (let j = i + 1; j < values.length; j++)
      if (values[i] === values[j]) return true
  return false
}