Placement Papers - NEC Corporation

Hi,

I'm Sudhakar Pandey. I attend the NEC. And in 1st round, there is a very difficult question.

Some questions are based on puzzles. And population, average, and percentage.

In the 1st round, there are 40 questions. 20 are quant and the next 20 are based on C output.
After this in the 2nd round, it is a coding round in which 4 questions are given to solve any 3.

My question is from the AVL tree, solve expression using bitwise operator, doubly linked list insertion and deletion at given pos. find the minimum of an array using recursion, and find the substring in the given string.

The papers are in two sets. 8 and 11. I got set 11 which is easy than set 8.
In the interview round the interviewer asked questions from the operating system, C output.
And ask link list. And tree. So prepare a whole link list and tree. And operating systems.
Questions are such as stack implementation, and how we find the mirror image of binary tree.

If there are num stored in the array from 1 to 1000 and one number is missing how do we find the missing num? Some questions are asked from C output.

All the best to all who attend NEC.