SDE - 1

Alice always loves to visit her garden and collect apples. The garden can be represented in the form of ‘N’ * ’N’ grid say ‘MATRIX’, where each cell of the grid can have one of the possible values:

1 -> The cell contains an apple that Alice can pick up and pass through it.

-1 -> The cell contains a bush and Alice can not visit this cell.

0 -> The cell is empty and Alice can pass through it.

Alice is present at the top left corner of the matrix or we can say at point (0,0).

Alice has to reach the bottom right corner of the matrix (‘N’-1,’N’-1) and return back to the starting point (0,0).

1. After picking an apple the cell will become empty.

2. While going towards the bottom right corner, Alice can either move Right or Down at each step.

3. While going towards the top left corner, Alice can either move Left or Up at each step.

4. If there is no path from (0,0) to (‘N’-1, ‘N’-1) then Alice will not pick any apple.

Your task is to help Alice to collect the maximum number of apples during her journey.

For example:

If the given matrix is :
[1, 1, -1, 1]
[1, 0, 1, 1]
[1, 1, 0, 1]
[0, -1, -1, 1]

One of the possible ways to collect maximum apples is :

Path for going towards bottom right corner: 
(0,0) -> (0,1) -> (1,1) -> (1,2) -> (1,3) -> (2,3) -> (3,3)

Apples collected are equal to 6.

Path for going towards top left corner:
(3,3) -> (2,3) ->(2,2) -> (2,1) -> (2,0) -> (1,0) -> (0,0)

Apples collected are equal to 3.

So Alice can collect a maximum of 9 apples.

You have been given a Binary Tree of distinct integers and two nodes ‘X’ and ‘Y’. You are supposed to return the LCA (Lowest Common Ancestor) of ‘X’ and ‘Y’.

The LCA of ‘X’ and ‘Y’ in the binary tree is the shared ancestor of ‘X’ and ‘Y’ that is located farthest from the root.

Note :

You may assume that given ‘X’ and ‘Y’ definitely exist in the given binary tree.

For example :

For the given binary tree

LCA of ‘X’ and ‘Y’ is highlighted in yellow colour.

It was to design a rate limiter .

You are given an array of integers ‘coins’ denoting the denomination of coins and another array of integers ‘freq’ denoting the number of coins of each denomination.

You have to find the number of ways to make the sum ‘V’ by selecting some(or all) coins from the array.

The answer can be very large. So, return the answer modulo 1000000007.

For Example :

‘N’ = 3, ‘coins’ = {1, 2, 3}, ‘freq’ = {1, 1, 3}, ‘V’ = 6

For the given example, we can make six by using the following coins:
{1, 2, 3}
{3. 3}
Hence, the answer is 2.

There was questions on Virtual memory and paging which are asked in college exams . Also some questions related to semaphores and locking were also discussed with practical use cases .

This was regarding multiple indexes and whats the difference between mysql and mongodb 
this is a standard interview question and i had already prepared this .

Why do you want to work here ? Any current that you hold ? Whats your expecations for salary ? etc