SDE - 2

You have been given an encoded string. Your task is to decode it back to the original string.

- An encoded string will be of the form <count>[encoded_string], where the 'encoded_string' inside the square brackets is being repeated exactly 'count' times. Note that 'count' is guaranteed to be a positive integer and can be greater than 9.
- There are no extra white spaces and square brackets are well-formed.

For example -

Input: 2[a]
“a” is encoded 2 times, hence the decoded string will be "aa".

Input: 3[a2[b]]
“b” is encoded 2 times, which decodes as 3[abb]. Now, "abb" is encoded 3 times, hence decoded string will be "abbabbabb". 

Alice and Bob have invented a new game to play. The rules are as follows -

First, they get a set of ‘N’ distinct integers. And then they take turns to make the following moves. During each move, either Alice or Bob (the player whose turn is the current) can choose two distinct integers ‘X’ and ‘Y’ from the set, such that the set doesn't contain their absolute difference |X - Y|. Then this player adds integer |X - Y| to the set (so, the size of the set increases by one).

If the current player has no valid move, he (or she) loses the game. The question is who will finally win the game if both players play optimally. Remember that Alice always moves first.

You have been given a long type array/list 'arr’ of size 'n’.

It represents an elevation map wherein 'arr[i]’ denotes the elevation of the 'ith' bar.

Print the total amount of rainwater that can be trapped in these elevations.

Note :

The width of each bar is the same and is equal to 1.

Example:

Input: ‘n’ = 6, ‘arr’ = [3, 0, 0, 2, 0, 4].

Output: 10

Explanation: Refer to the image for better comprehension:

Note :

You don't need to print anything. It has already been taken care of. Just implement the given function.

You are given an array “A” of N integers. Your task is to find the maximum element in all K sized contiguous subarrays from left to right.

For Example:

If A = [3, 2, 3], and K = 2.
Then max of [3, 2] = 3 and max of [2, 3] = 3
So, the answer will be [3, 3]

If A = [3, 2, 3, 5, 1, 7] and K = 3.
Then max of [3, 2, 3] = 3 
Then max of [2, 3, 5] = 5 
Then max of [3, 5, 1] = 5 
Then max of [5, 1, 7] = 7 
So  the answer will be [3, 5, 5, 7]

Follow Up :

Can you solve the problem in O(N) time complexity and O(K) space complexity?

Singleton pattern - build a class that returns DB connection

What is multi threading?

What do you mean by exception handling?

You are given two Singly Linked Lists of integers, which may have an intersection point.

Your task is to return the first intersection node. If there is no intersection, return NULL.

Example:-

The Linked Lists, where a1, a2, c1, c2, c3 is the first linked list and b1, b2, b3, c1, c2, c3 is the second linked list, merging at node c1.

1. What are Java Collections?
2. What is the difference between Set, List, and Map interfaces?
3. What is the difference between ArrayList and LinkedList?
4. How does the HashSet ensure uniqueness of elements?
5. Explain the Comparable and Comparator interfaces.