SDE - Intern

You are given a Singly Linked List of integers. You have to return true if the linked list is palindrome, else return false.

A Linked List is a palindrome if it reads the same from left to right and from right to left.

Example:

The lists (1 -> 2 -> 1), (3 -> 4 -> 4-> 3), and (1) are palindromes, while the lists (1 -> 2 -> 3) and (3 -> 4) are not.

You have been given string 'S' of length 'N' that may contain duplicate alphabets. Your task is to return the count of distinct subsequences of it.

For example:

For the given string “deed” :
The possible subsequences are {“”}, {“d”}, {“e”}, {“de”}, {“e”}, {“de”}, {“ee”}, {“dee”}, {“d”}, {“dd”}, {“ed”}, {“ded”}, {“ed”}, {“ded”}, {“eed”} and {“deed”}.

As, {“d”}, {“e”}, {“de”}, {“ed”} and {“ded”} are repeated. 

The distinct subsequences are {“”}, {“d”}, {“e”}, {“de”}, {“ee”}, {“dee”}, {“dd”}, {“ed”}, {“ded”}, {“eed”} and {“deed”}

Thus, the output will be 11. 

Note:

As the answer can be large, return your answer modulo 10^9  + 7.  

Given a singly linked list of integers. Your task is to return the head of the reversed linked list.

For example:

The given linked list is 1 -> 2 -> 3 -> 4-> NULL. Then the reverse linked list is 4 -> 3 -> 2 -> 1 -> NULL and the head of the reversed linked list will be 4.

Follow Up :

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

You have been given two strings ‘STR1’ and ‘STR2’.

Your task is to find if ‘STR1’ is a subsequence of ‘STR2’.

A subsequence of a string is a new string that can be derived from the original string by deleting some characters (can be none) without changing the relative ordering of other characters.

Example:

‘ACE’ is a subsequence of ‘ABCDE’ because ‘ACE’ can be formed by deleting ‘B’ and ‘D’ without changing the relative order of characters. ‘ADB’ is not a subsequence of ‘ABCDE’ because we can get ‘ABD’ from ‘ABCDE’ but not ‘ADB’ and in ‘ADB’ relative order of ‘B’ and ‘D’ are different from original strings.

Note:

1.Strings ‘STR1’ and ‘STR2’ consists only of English uppercases.

2.Length of string ‘STR2’ will always be greater than or equal to the length of string ‘STR1’.

Example:

For example, the given ‘STR1’ is ‘BAE’ and ‘STR2’ is ‘ABADE’. 
String ‘STR1’ is a subsequence of string ‘STR2’ because ‘BAE’ can be formed by deleting ‘A’ and ‘D’ from ‘ABADE’ and the relative ordering of the characters of the string ‘ABADE’ persists.

You have been given a board where there are '2' rows and 'N' columns. You have an infinite supply of 2x1 tiles, and you can place a tile in the following ways:

1. Horizontally as 1x2 tile
2. Vertically as 2x1 tile

Count the number of ways to tile the given board using the available tiles.

Note :

The number of ways might be large so output your answer modulo 10^9 + 7.

Here an example of tile and board for 'N' = 4 :

There are 3 jars, namely, A, B, C. All of them are mislabeled. Following are the labels of each of the jars:A: CandiesB: SweetsC: Candies and Sweets (mixed in a random proportion)You can put your hand in a jar and pick only one eatable at a time. Tell the minimum number of eatable(s) that has/have to be picked to label the jars correctly. (Learn)