#Strings

Given a string, find the length of the longest substring that contains all unique characters. Explain your approach and provide a solution with its time complexity.

In a stream of characters, determine which character has the kth highest frequency. If two characters have the same frequency, return the one that appears first in the stream. Example: If the input is 'abracadabra', k = 2, the output should be 'a'.

Given a string, find all the anagrams that can be formed using the characters of that string. Return a list of all grouped anagrams sorted in a specific order.

Given two strings, find the length of their longest common subsequence. A subsequence is a sequence that appears in the same relative order, but not necessarily contiguous. For example, given strings 'abcde' and 'ace', the longest common subsequence is 'ace' with length 3.

Write a function to check if a given string is a palindrome. A palindrome reads the same backward as forward.