What is the difference between NCHAR, CHAR, NVARCHAR and VARCHAR

A good information with explanation is found here
http://www.sql-server-helper.com/faq/data-types-p01.aspx

See how you would solve these known algorithm problems

Array reversal in Recurrsion

binary tree problems with solution

Get maximum occurring character

Finding missing numbers from billion sequential number list file

Implementing tokenizer and adding tokens to the linked list

Find the first occurence of number in the sorted array

String Ordered Permutation Algorithm Problem

Java solution for checking anagram strings – tell if phrases are anagrams

find longest word in the sentence

testing k complementary pairs algorithm with junit