Session#55 on Strings - Unique Chars and permutation

Description:
Here are the problems we discussed in Saturday's session and their code link.
Q1: Has Unique characters: Check if a string has all unique characters. (Page 192- CTCI- 6th edition)
Q2. Check Permutation: Given two strings, write a method to decide if one is a permutation of the other (Page 193- CTCI 6th edition)
Q3: Max Occurrences: Given a string , find the character that occurred maximum times.
Code link: https://onlinegdb.com/uFNxzJX30