SDE - 1

For a given array with N elements, you need to find the length of the longest subsequence from the array such that all the elements of the subsequence are sorted in strictly increasing order.

Strictly Increasing Sequence is when each term in the sequence is larger than the preceding term.

For example:

[1, 2, 3, 4] is a strictly increasing array, while [2, 1, 4, 3] is not.

You have been given a string ‘S’.

You must return the string ‘S’ sorted in decreasing order based on the frequency of characters.

If there are multiple answers, return any of them.

Example :

Let 'S'= “abAb”. 

Here the characters ‘a’ and ‘A’ have frequency 1 and character ‘b’ has frequency ‘2’.  

Therefore the sorted string is “bbAa”. 

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?

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