Re: [Haskell-cafe] Time and space complexity of "take k . sort"

Paul Johnson writes:

...

takeLargest k = take k . sort

But of equal practical interest is the space complexity. The optimum algorithm is to take the first k items, sort them, and then iterate through the remaining items by adding each item to the sorted list and then throwing out the highest one. That has space complexity O(k). What does the function above do?

Well - 'sort' doesn't know the value of 'k', so it needs to retain all elements, just in case 'k' might be 'n'. So I don't see how you can use space less than 'n' for a construct like the above. -k -- If I haven't seen further, it is by standing in the footprints of giants