Kucharskimaciej your comment above is incorrect. +v is not an equivalent of parseInt(v, 10). It is, in fact, an equivalent of Number(v). The '+' operator is a shorthand to coerce each 'v' from a string to a number.

This might seem like splitting hairs, but it’s a critical point for others to understand this shorthand in a broader context.

In the solution above, we see that 'int' is already coerced into a number because of the *256. If we step through the first loop of the reduce method without coercing 'v', we can see how the sum would change — 128 * 256 + "32" // "3276832" (INCORRECT) vs 128 * 256 + 32 // 32800 (CORRECT). Without coercing 'v' you actually coerce 'int' back into a string and concatenate 'v'

+v is an equivalent of parseInt(v, 10)

I've been thinking about this recently too. It would be nice to keep track of your solution runtimes, and I was thinking that for some katas, it might even be nice to be able to compare solution runtimes with other users. However, the issue is that these solutions probaby run on different hardware at different times, so the results from different runs probably aren't comparable in an apples-to-apples sense. It still might not be an intractible problem, though.

cost time?