As a weekend project, I created a service to monitor the status of many services (Github included) in one single page http://isserviceup.com/ . You can register with your Github account and star the services you use to receive notifications through Slack when their status change. It's all free and open source, let me know your thoughts!
Plex for iOS and Android is just a front end, you need the server-side of the software to convert video.
XBMC can convert video on-the-fly, to do this on iOS it uses private API for hardware acceleration (and that's why you need to jailbreak your device to install it)
The second solution works in linear time only if one assumes that multiplication is a constant time operation. But is it really? If you look at how a processor does multiplication it becomes clear it is a O(log n) operation where n is one of the numbers being multiplied. Thus, the second solution is probably a O(nlogn) solution.
Sum of first n natural numbers is n(n+1)/2. The sum of the array, represented by s, is n(n+1)/2 - x + y (subtract x - the missing number and add y - the duplicated number) gives:
1: n(n+1)/2 - x + y = s
Product of first n natural numbers is represented as: n! The product of the numbers in array is p.
2: p x / y = n!
(multiply by x - add missing number to product and divide by y - remove duplicated number from product).
