SDE - 1

You are given a 2D board('N' rows and 'M' columns) of characters and a string 'word'.

Your task is to return true if the given word exists in the grid, else return false. The word can be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or vertically neighboring.

Note:

The same letter cell should not be used more than once.

For Example:

For a given word “design” and the given 2D board 
[[q’, ‘v’, ‘m’, ‘h’],
 [‘d’, ‘e’, ‘s’, ‘i’],
 [‘d’, ‘g’, ‘f’, ‘g’],
 [‘e’, ‘c’, ‘p’, ‘n’]]

The word design can be formed by sequentially adjacent cells as shown by the highlighted color in the 2nd row and last column.

Given a leaderboard of a game with the following ranking pattern:

The player with the highest score is ranked number 1 on the leaderboard.

Players who have equal scores receive the same ranking number, and the next player(s) receive the immediately following ranking number.

You are given game scores of a player of ‘M’ rounds. Your task is to return the position obtained in each round.

Note:

The leaderboard scores are in descending order.
The game scores are given in ascending order.

You are given an array of 'N' integers, and a positive integer 'K'. You need to determine if it is possible to divide the array into 'K' non-empty subsets such that the sum of elements of each subset is equal.

Note:

1. The array can have duplicate elements.

2. Each of the array elements must belong to exactly one of the 'K' subsets.

3. The elements chosen for a subset may not be contiguous in the array.

You are given a positive integer ‘N’. Your task is to print all prime numbers less than or equal to N.

Note: A prime number is a natural number that is divisible only by 1 and itself. Example - 2, 3, 17, etc.

You can assume that the value of N will always be greater than 1. So, the answer will always exist.

There are ‘N’ people at a party. Each person has been assigned a unique id between 0 to 'N' - 1(both inclusive). A celebrity is a person who is known to everyone but does not know anyone at the party.

Given a helper function ‘knows(A, B)’, It will returns "true" if the person having id ‘A’ know the person having id ‘B’ in the party, "false" otherwise. Your task is to find out the celebrity at the party. Print the id of the celebrity, if there is no celebrity at the party then print -1.

Note:

1. The helper function ‘knows’ is already implemented for you.
2. ‘knows(A, B)’ returns "false", if A doesn't know B.
3. You should not implement helper function ‘knows’, or speculate about its implementation.
4. You should minimize the number of calls to function ‘knows(A, B)’.
5. There are at least 2 people at the party.
6. At most one celebrity will exist.

You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to return the list of all pairs of elements such that each sum of elements of each pair equals 'S'.

Note:

Each pair should be sorted i.e the first value should be less than or equals to the second value. 

Return the list of pairs sorted in non-decreasing order of their first value. In case if two pairs have the same first value, the pair with a smaller second value should come first.