Interviewed Oct 2009 in Bellevue, WA (took 3 days)

Data structure related questions. Algorithms and white boarding question over the phone. like
1 "Write a function that counts the number of primes in the range [1-N].
2"Write a function that will return the number of days in a month (no using System.DateTime)
3.Write a function that inserts an integer into a linked list in ascending order. Write the test cases for this function..
4.Given an array of characters which form a sentence of words, give an efficient algorithm to reverse the order of the words (not characters) in it.
5.Give a very good method to count the number of ones in a "n" (e.g. 32) bit number.
6.You're given an array containing both positive and negative integers and required to find the sub-array with the largest sum (O(N) a la KBL).
7Write a routine in C for the above. Given an array of characters. How would you reverse it. ? How would you reverse it without using indexing in the array.
And some tricky questions like There are four dogs/ants/people at four corners of a square of unit distance. At the same instant all of them start running with unit speed towards the person on their clockwise direction and will always run towards that target. How long does it take for them to meet and where?