Beefy Boxes and Bandwidth Generously Provided by pair Networks
Syntactic Confectionery Delight
 
PerlMonks  

Re^3: Common Perl Pitfalls

by JavaFan (Canon)
on Apr 10, 2012 at 13:22 UTC ( #964321=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Common Perl Pitfalls
in thread Common Perl Pitfalls

Care to elaborate on that "quadratic" comment?
Say you want to delete all elements in the second half of the array. The first N/2 iterations of your loop, no splicing happens. But on the N/2 + 1st iteration, the splicing takes at least N/2 - 1 steps, as that many array elements need to be moved. On the N/2 + 2nd iteration, the splicing takes at least N/2 - 2 steps. In total, you will be moving

ΣN/2-1i=1(i)

array elements. If I've done my math correctly, the above sum equals (N2 - 2N + 4)/8. Which means your algorithm runs in Ω(N2) time.


Comment on Re^3: Common Perl Pitfalls
Re^4: Common Perl Pitfalls
by Joe_ (Beadle) on Apr 10, 2012 at 18:10 UTC

    Wonderful. Thanks for enlightening me...

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://964321]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others lurking in the Monastery: (9)
As of 2014-10-22 09:18 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    For retirement, I am banking on:










    Results (114 votes), past polls