Twitter interview questions

1. Maze solver
2. Gmail architecture design
1. http://netlojava.blogspot.com/2013/08/gmail-server-architecture.html 
2. http://css.dzone.com/news/gmail-architecture-part-1 
3. Given a two strings, return whether the second is an anagram of a palindrome of the first string.
4. Online Machine Learning
5. Graph Algorithm
6. Bit manipulation
7. Get unfair coins using fair coins https://dicedcoins.wordpress.com/2012/07/30/simulate-fair-coins-unfair/ 
8. Determine if a BST is valid or not
9. 1) Find the single number in a array, all other elements are paired. 2) Give a array A[k], define the set S{k} := { A[k], A[A[k]], A[A[A[k]]], ... }, write program to count the maximum size of Sks.
10. integer N and returns an NxN matrix with incrementing integers in a spiral, from outside in.  
11. Overlap intervals
12. Top k terms in unsorted array
13. In order iterative bst traversal
14. Questions given a vector of strings of length n with each word having a length of m on average, group all anagrams into a cluster. Do this for the case that n >>>>>> m and in the most efficient way possible. Assume extra space allowed.
15. Given a number, tell how many 1s are there in the binary format of this number
16. http://stackoverflow.com/questions/2344496/how-can-i-print-out-all-possible-letter-combinations-a-given-phone-number-can-re 
17.   http://www.lifeincode.net/programming/leetcode-letter-combinations-of-a-phone-number-java/
18. Tree to ordered double linked list
19. Implement hash table
20. Given n sets of choices: (1,2,3), (2,3,4), (4,5)
    
    You pick one element from each set of choices.
    
    Generate all possible picking.
21. Trie
22. Subset sum
23. Topological sorting
24. Implement divide operation using multiply
25.  http://javahungry.blogspot.com/2014/05/convert-math-number-to-equivalent-readable-word-in-java-code-with-example.html
26.  http://leetcode.com/2010/09/print-all-combinations-of-number-as-sum.html
27. http://rleetcode.blogspot.com/2014/02/combination-sum.html 
28. 4SUm
29. Given two nodes in a binary tree find the number of nodes, between the path to the two nodes
30.  LRU cache
31. Given sorted dictionary, sort the characters
32. Given a list of names. Find whether a particular name occurs inside a given tweet or not. If found return true otherwise false Time complexity should be less than O(n).  - suffix tree
33. Given the pre-order sequence of a binary tree, how many trees can be created from this
34. Validate if a tree is BST
35. 4 points form a square
36. http://www.careercup.com/question?id=14951746
37. Design a hashmap
38. Design a thread safe hashtable
39. Design a collaborative editor - where each participant can go offline
40. Given a string representing roman numeral, find and return its numeric value. e.g. XXIV = 24 and so on. 
41. Top K queries from search logs
42.  
43. •  
    • Output : (*, *, *), (*, *, c), (*, b, *), (*, b, c), (a, *, *), (a, *, c), (a, b, *), (a, b, c)   Answer Question
    • Convert infix expression into postfix.   Answer Question
    • Write code that walks thru all src code starting from a root dir. and create histogram of number of characters per line across all files.