SDE - Intern

Given a singly linked list of integers. Your task is to return the head of the reversed linked list.

For example:

The given linked list is 1 -> 2 -> 3 -> 4-> NULL. Then the reverse linked list is 4 -> 3 -> 2 -> 1 -> NULL and the head of the reversed linked list will be 4.

Follow Up :

Can you solve this problem in O(N) time and O(1) space complexity?

You are given a 2D matrix 'ARR' (containing either ‘0’ or ‘1’) of size 'N' x 'M', where each row is in sorted order.

Find the 0-based index of the first row with the maximum number of 1's.

Note :

If two rows have the same number of 1’s, return the row with a lower index.

If no row exists where at-least one '1' is present, return -1.

Example:

Input: ‘N’ = 3, 'M' = 3
'ARR' = 
[     [ 1,  1,  1 ],
      [ 0,  0,  1 ],
      [ 0,  0,  0 ]   ]

Output: 0

Explanation: The 0th row of the given matrix has the maximum number of ones.

Design patterns familiar with and used and asked about Singleton

Two roads and only one sided traffic at a time is allowed. Code for synchronization to avoid deadlock 

Counting semaphore problem in which a resource as N instances.Synchronizing access to resource .

Design and implement a data structure for Least Recently Used (LRU) cache to support the following operations:

1. get(key) - Return the value of the key if the key exists in the cache, otherwise return -1.

2. put(key, value), Insert the value in the cache if the key is not already present or update the value of the given key if the key is already present. When the cache reaches its capacity, it should invalidate the least recently used item before inserting the new item.

You will be given ‘Q’ queries. Each query will belong to one of these two types:

Type 0: for get(key) operation.
Type 1: for put(key, value) operation.

Note :

1. The cache is initialized with a capacity (the maximum number of unique keys it can hold at a time).

2. Access to an item or key is defined as a get or a put operation on the key. The least recently used key is the one with the oldest access time.