6 - Total Salaries / is the solution overkill?

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I pass all the tests with a few lines of code.
When I look at the provided solution I want to run away!

Can anyone tell me why my solution is missing compare to the given solution?

function calculateTotalSalaries(data) {
    // Write your code here
  let res = 0
  

  for (const key in data) {
    if (Array.isArray(data[key])) {
      res += data[key].map(x => x.salary).reduce((acc, item) => acc + item, 0)
    } else {
      res += calculateTotalSalaries(data[key])
    }
  }
  return res
}