SDE - Intern

You are given a singly Linked List of integers. Your task is to return true if the given singly linked list is a palindrome otherwise returns false.

For example:

The given linked list is 1 -> 2 -> 3 -> 2-> 1-> NULL.

It is a palindrome linked list because the given linked list has the same order of elements when traversed forwards and backward​.

Follow Up:

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

A Derangement is a permutation of ‘N’ elements, such that no element appears in its original position. For example, an instance of derangement of {0, 1, 2, 3} is {2, 3, 1, 0}, because 2 present at index 0 is not at its initial position which is 2 and similarly for other elements of the sequence.

Given a number ‘N’, find the total number of derangements possible of a set of 'N’ elements.

Note:

The answer could be very large, output answer %(10 ^ 9 + 7).

You are given two strings S and X containing random characters. Your task is to find the smallest substring in S which contains all the characters present in X.

Example:

Let S = “abdd” and X = “bd”.

The windows in S which contain all the characters in X are: 'abdd', 'abd', 'bdd', 'bd'. 
Out of these, the smallest substring in S which contains all the characters present in X is 'bd'. 
All the other substring have a length larger than 'bd'.

You are given a binary tree in which each node contains an integer value and a number ‘K’. Your task is to print every path of the binary tree with the sum of nodes in the path as ‘K’.

Note:

1. The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to child nodes).

2. Output the paths in the order in which they exist in the tree from left to right. Example: In the below example, path {1,3} is followed by {3,1} and so on.

Example:

For K = 4 and tree given below:

The possible paths are:
1 3
3 1
-1 4 1
4 
-1 5

The sum of values of nodes of each of the above-mentioned paths gives a sum of 4.