1. To make a spiral(I don't remember problem statement but solution was to print the 'nos in a 2d matrix' in spiral form)
2. Reverse half of Linked List(In. 1->2->5->7->8->3 output: 1->2->5->3->8->7 ).

1. In the series (1234567891011121314....) print nth character eg(9th character is 9, 10th character is 1, 11th charcter is 0, 12th is 1. and so on).
2. Basic questions on trees, traversals etc.

Given arrival and dept. time of n trains. find no of platform required on the station so that all trains can stop on station. (Train scheduling algo). Condition was to solve the problem with each condition
1. sorting is allowed without extra space
2. extra space O(n) allowed but sorting is prohibited.

Interview was good, What is important is to be sure before answering, it's ok if you are not able to answer all questions. All the best :)