1) find all possible buddy words from the given list of strings(lower alpa).
eg. for abc buddy is cde, gyr --> hzs

2) Similar to Merge Intervals

3) Similar to https://leetcode.com/problems/swim-in-rising-water/description/

4) There is a chess contest between N players. Each chess player has a distinct rank (positive integer number from 1 to N).
We assume that in a chess game between two players, the player ranked higher always wins. The ranks remain constant during the contest.
Unfortunately, we don't know the player ranks. But we know the outcome of M games in the following format:
Player #1 won #2
Player #2 won #4
...
Given the results of M games above, are there any players whose rank can be precisely determined?

5) Consider a social network with n users. You have been given vector<vector< int >> friends. where friends[i][0] and friends[i][1] are friends. A person 'a' can view profile of 'b' if he is friend or has a indirect common friend. Find out how many profiles can each user view.
Constraint :
n <= 10 ^ 5
friends.size() <= n
E.g. :
n = 7
friends = [{1,2}, {2,3}, {3,4}, {5,6}, {6,7}]
result = [4,4,4,4,3,3]

6) Given a string 's' find the no. of unique palindromic substrings.
Constraints :
s.size() <= 5000
E.g. :
s = "aacaa"
result = 5 ["a", "c", "aa", "aca", "aacaa"]

7) You are given multiple cities and a city A, each city is at a distance represented by time it takes to reach it. You are given n favorite cities, find the shortest time to reach any of the favorite cities and return the time required to reach favorite

8) Given a binary tree, return true if all the values of node are equal
Given a binary tree, return maximum binary sub tree size where all values of node are equal
        2
    2	    2
2  	  2  2      3
ans: 3

9) String expression evaluation
Ex: 2a+2b-(a-b)
Ans: a+3b

10) Imagine you are standing at an incoming conveyor belt of items that need to be packaged into boxes of exactly three items that all fit together and placed on a second, outgoing, conveyor belt. You have sufficient storage space to place items off to the side while you wait for a full triplet that all fit together.
Conveyor belt items are floating point numbers. Three items that "fit together" means that all items are within distance d of each other. Once a 3 tuple is formed, those items must be discarded (should not be considered for future tuples).
input_stream = [1.0, 11.0, 12.0, 13.0, 2.0, 3.0]
d = 3
Output:
[[11.0, 12.0, 13.0], [1.0, 2.0, 3.0]]
Distance is calculated by absolute values of the items for example
|1.0-2.0| = 1 <= 3
|2.0 - 3.0| = 1 <= 3
|1.0-3.0| = 2 <= 3
Input will not be given as an array but instead is a stream of numbers.
Follow Up
If instead of just floating point numbers, you were given points on an X-Y plane, how would you modify the solution?

11) Given a node in a Binary Search Tree (BST), find the next largest (inorder successor) and next smallest (inorder predecessor) node. It is guaranteed that these nodes always exist (i.e the input node will never be the smallest or largest node in the BST).
You are only given a pointer to the node, and each node has a parent pointer.
The structure is as follows:
struct Node {
    int value;
    Node* left_child;
    Node* right_child;
    Node* parent;
};
Consider this BST:
        4
       / \
      2   6
     / \ / \
    1  3 5  7
If the given node is 3, the next largest (successor) is 4, the next smallest (predecessor) is 2.

12) Given a source, destination and corrupted node, find if it is possible to reach the destination from the source.
This is a straightforward BFS / DFS question. Just don't traverse the corrupted node.
Follow Up
Return the minimum distance of every node from the source node. The edge weights can all be considered as 1.

13) Given 2 strings, return if they are buddies. 2 strings are buddies if the distance between each char of the strings is the same. dist('a', 'b') = 1 and dist('b', 'a') = 25. Also, dist('z', 'a') = 1.
Follow Up
Given a list of strings, group all buddies together.

14) You are given a list of N elements. Each element is a tuple (value, can_decrement) where:
value is an integer (positive or negative),
can_decrement is a boolean indicating how the value can be adjusted:
If True, you are only allowed to decrement the value.
If False, you are only allowed to increment the value.
You are allowed to increment/decrement each number as much as you want, but only in the allowed direction. Your task is to determine whether it's possible to transform all values into a valid permutation of [1, 2, ..., N].
If it's possible, return the mapping in the form {original: transformed}
If it's not possible, return an empty dictionary.
Follow Up
How many elements can be moved from the decrement list to the increment list and still allow a permutation to be made?

15) https://leetcode.com/problems/move-pieces-to-obtain-a-string/description/

16) You have a very very big number 2123470299109372 and a given integer k [let's say k=6], you need to find largest k digit number which is a subsequence of the original number. ans=999372

17) Gift Buying Problem
    An uncle wants to buy gifts for his nephew. The nephew provides a list of gifts, where each gift has:
        day: The day the gift is available for purchase
        price: The cost of the gift on that day
    Example:
    3 4
    4 2
    6 4
    10 5
    The uncle saves $1 per day and can only buy a gift on the specified day. If he skips a gift, he cannot buy it later. The goal is to determine the maximum number of gifts he can purchase.

18) Building Occupancy Problem
    Given security logs with timestamps for entry and exit of users, determine:
        The maximum occupancy of the building at any given time.
        The time at which that peak occupancy occurred.

19) Given an integer n, return a license plate number following this pattern:
Ranges:
    00000-99999
    A0000-Z9999
    AA000-ZZ999
    AAA00-ZZZ99
    AAAA0-ZZZZ9
    AAAAA-ZZZZZ
Helper Functions Provided:
    padToBeginning(reqLen, charToPad, value): Pads the given character at the beginning of a string to achieve the required length.
        Example: padToBeginning(9, '0', '123') = 000000123
    alpha(value): Converts an integer into an alphabetic sequence.
        Example: alpha(0) = A, alpha(25) = Z, alpha(26) = AA

1) You are designing a JSON webpage viewer with the ability for users to save and ldad previously viewed JSON documents.
The website sends/receives the complete state of the world from the webpage to the backend server on each update/save.
The state of the world is stored in SimpleJSON. The client has the original document D1 and the modified document D2, where D2 is D1 + (delta)
You begin profiling the application and notice that for very large JSON documents being saved it's very slow -- even if no change has been produced!
Optimise the space-efficiency of saving the changes for a given SimpleJSON document where you are given 'old_doc' and 'new_doc'.
Follow up :
Json can be nested json.

2) A linked list problem where each node contains a value, a next pointer, and a hash computed using the current node’s value and its next node.
Tasks included:
Insert a node at the head of the list
Validate the linked list by traversing and verifying the hash of each node
Inserting a node at position k using recursion (which requires updating the hash values of all nodes from position k up to the head)

3) Shall I ask help on How to solve below problem-
For given intervals inputs [from, to, name], return non-overlapping intervals [from, to, name(s)].
Example:
Input
[10, 100, David]
[50, 150, Alex]
[200, 300, Joe]
Output
[10,50, David]
[50, 100, (David, Alex)]
[100, 150, Alex]
[200, 300, Joe]

4) https://leetcode.com/problems/design-search-autocomplete-system/description/

5) movie recommendation system. Each movie has a title and a rating, if the process has marked movie A as similar to movie B, and movie B similar to movie C, we will also consider movie A as similar to movie C
Given a movie from the list, return its N similar movies with highest rating.
For example, if we have the following four movies:
"Movie A" with rating 6
"Movie B" with rating 7
"Movie C" with rating 8
"Movie D" with rating 9
and the process has determined the following similarities:
"Movie A" is similar to "Movie B"
"Movie B" is similar to "Movie C"

6) Find indices of ranges where a number lies. (https://leetcode.com/problems/most-beautiful-item-for-each-query/description/)
ranges = {3 , 9} , {2 , 8} , {5 , 10}
f(3) should return { 0 , 1}
f(9) should return {0 , 2}

7) You have sequence array, each sequence has some value in order. You have to create a result
where order of sequence stays as it is.
Ex - [
[1,2,15,8],
[2,4,7,8],
[2,3,7,15]
]
Output - 1,2,3,4,7,15,8 or 1,2,4,3,7,15,8
False case - [[1,6,4], [4,1]] -

8) number of 3 * 3 submatrics, which have maximum number of one's. given current matrics is of size n * m (where n >=3 and m >= 3)

9) I was given a question during an interview where some strings were associated with points, like:
[
  ["cat.animal", 5],
  ["animal", 10],
  ["lion.animal", 15],
  ["tiger.cat.animal", 20]
]
Each string contributes its points to itself and any of its parent nodes. The goal was to return only the leaf strings (i.e., strings that don't have any children) along with their total aggregated points.
Below is expected output
[
  ["lion.animal", 25],  # 15 (self) + 10 (animal)
  ["tiger.cat.animal", 35]  # 20 (self) + 10 (animal) + cat.animal(5)
]
Only two leaf nodes exist in this case: lion.animal and tiger.cat.animal.

10) arr = [1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1]
Goal:
Find the maximum continuous window where all elements are 0.
Follow-up
Given that we can flip at most K 1s to 0s, find the longest window that becomes all zeros after flipping.

10) given two city A and B, where you need to collect profit and cost of switching between the cities was given as negative like -5. find the maximum profit you can collect given you can start from any city and switch as many time you want.
A = [2, 3, 4, 5 ,6]
B = [4, 3, 6, 5 ,8]
switch Cost = -5

11) The question was to create a string replacement library. Given a map of string replacements, replace the value in the input string.
Example:
Map: {USER => admin, HOME => /%USER%/home}
Input: I am %USER% My home is %HOME%
Output: I am admin My home is /admin/home
Follow-up
He later modified the question to include something like a loop. We need to figure out how to detect and handle that.
Example:
Map: {USER => admin, HOME =>/%USER%/%PATH%/, PATH => %HOME%}

12) Given multiple files, we want to find the maxmimum matching prefix between any 2 files.
Sample input
String[] file1 = {"hello", "world", "abc", "xyz"};
String[] file2 = {"hello", "world", "abc", "xyz1"};
String[] file3 = {"hello", "world", "abc2", "xyz"};
String[] file4 = {"hello", "world", "abc1", "xyz2"};
Answer for this is 3 "hello", "world", "abc" matches in file1 and file2

13) Problem: Given a chat log file, find the top N most talkative users along with their total word count.
Example Log:
10:00 < John > Hi, How is everyone?
10:05 < Amy > Hello John
10:06 < Maria > Great, Having my morning coffee
13:00 < John > Let's meet this weekend
13:30 < Amy > Woahoo
Helper Function Provided:
    parseLog(filepath): Returns the word count of each message.
        Example Output:
        [{'John', 4}, {'Amy', 2}, {'Maria', 5}, {'John', 4}, {'Amy', 1}]
Follow-up Questions:
    Optimize for better complexity.
    Implement the parseLog() function.

14) Given an unweighted and undirected graph, there are some friends on some nodes and there are some cafes on some nodes. We want to find such a cafe that the maximum distance travelled by any of the friend is minimal.
Sample input
Friends - 1,7
Cafes - 5,6
Edges - 1 2, 2 3, 3 4, 4 5, 3 6, 7 5, 7 3
Distance friend 1 has to travel to reach cafe 5 and 6 is 4 and 3
Distance friend 7 has to travel to reach cafe 5 and 6 is 3 and 2
Cafe 6 is the answer since max distance travelled by both friends is less compared to cafe 5.
If its impossible to reach a cafe then return null.
There could be cycles in graph.