Terry wrote: > hi, > this is regarding a problem from programming pearls by jon bentley > column 5. > I have few questions , > 1) how to check if an array is sorted or not. Can it be done it sub - > linear time
No, if you don't look at all n elements, there's no way to no if it's sorted. > 2) In section 5.8 problem 5, he describes saying that checking a array > is sorted or not takes n-1 operations. How can you add partial checking > to the function at significantly less cost. I suspect he's talking about binary search. A common mistake is to apply binary search on a non-sorted array. Checking whether the array is sorted each time would ruin the main benefit of binary search (logarithmic time). Instead, you could verify that the log n elements binary search probes (and perhaps they're immediate neighbors) are in the right order. This partial checking takes only O(log n) time. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algogeeks@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/algogeeks -~----------~----~----~----~------~----~------~--~---
