SDE - 1

You are given an array 'arr' of length 'n'. Find the index(0-based) of a peak element in the array. If there are multiple peak numbers, return the index of any peak number.

Peak element is defined as that element that is greater than both of its neighbors. If 'arr[i]' is the peak element, 'arr[i - 1]' < 'arr[i]' and 'arr[i + 1]' < 'arr[i]'.

Assume 'arr[-1]' and 'arr[n]' as negative infinity.

Note:

1.  There are no 2 adjacent elements having same value (as mentioned in the constraints).
2.  Do not print anything, just return the index of the peak element (0 - indexed).
3. 'True'/'False' will be printed depending on whether your answer is correct or not.

Example:

Input: 'arr' = [1, 8, 1, 5, 3]

Output: 3

Explanation: There are two possible answers. Both 8 and 5 are peak elements, so the correct answers are their positions, 1 and 3.

Given two strings, ‘A’ and ‘B’. Return the shortest supersequence string ‘S’, containing both ‘A’ and ‘B’ as its subsequences. If there are multiple answers, return any of them.

Note: A string 's' is a subsequence of string 't' if deleting some number of characters from 't' (possibly 0) results in the string 's'.

For example:

Suppose ‘A’ = “brute”, and ‘B’ = “groot”

The shortest supersequence will be “bgruoote”. As shown below, it contains both ‘A’ and ‘B’ as subsequences.

A   A A     A A
b g r u o o t e
  B B   B B B  

It can be proved that the length of supersequence for this input cannot be less than 8. So the output will be bgruoote.

You have been given a binary matrix of size 'N' * 'M' where each element is either 0 or 1. You are also given a source and a destination cell, both of them lie within the matrix.

Your task is to find the length of the shortest path from the source cell to the destination cell only consisting of 1s. If there is no path from source to destination cell, return -1.

Note:

1. Coordinates of the cells are given in 0-based indexing.
2. You can move in 4 directions (Up, Down, Left, Right) from a cell.
3. The length of the path is the number of 1s lying in the path.
4. The source cell is always filled with 1.

For example -

1 0 1
1 1 1
1 1 1
For the given binary matrix and source cell(0,0) and destination cell(0,2). Few valid paths consisting of only 1s are

X 0 X     X 0 X 
X X X     X 1 X 
1 1 1     X X X 
The length of the shortest path is 5.

Given a string S containing digits from 2 to 9 inclusive. Your task is to find all possible letter combinations that the number could represent.

A mapping from Digits to Letters (just like in Nokia 1100) is shown below. Note that 1 does not map to any letter.

You are given an integer 'N'. For a given 'N' x 'N' chessboard, find a way to place 'N' queens such that no queen can attack any other queen on the chessboard.

A queen can be killed when it lies in the same row, or same column, or the same diagonal of any of the other queens. You have to print all such configurations.

You are given a string ‘STR’. Your task is to find the shortest palindrome that can be formed by adding characters in front of ‘STR’.

For example:

You are given ‘STR’ = “aabcd”. Then our answer will be “dcbaabcd”. We can form a palindrome by adding ‘d’, ‘c’, and ‘b’ in front of ‘STR’.