Software Engineer

Step 1 : I orally provided the brute force method i.e using 2 loops but indicated that I won't be going with this solution.
Step 2 : I used dictionary(hashmap) to store the first occurrence of a character's index
Step 3 : I looped through the string to find out the repeated occurrence of a given character and evaluating if the first one forms the biggest substring or the second one, and stored the indices of the respective substring character in the mapping.

Step1 : I used a hash table to hash all the individual digits to letter combinations.
Step 2 : I used a helper function which runs recursively until all the combinations have been computed
Step 3 : Store unique combinations in a hash map so that repetitive calls from recursion loop may not be necessary.

Tip 1 : Think of all the variables in this problem and separate them according to the use case of their interactions.
Tip 2 : For eg: we know we need a match class which registers both the teams, date, venue and the outcome. 
Tip 3 : Don't lose yourself in the design, always keep the main function in mind which runs the code. If the dry run test fails, no amount of good design pattern would get you selected.

Tip 1 : Be always respectful when asked about your previous employer. It's a bad look if you start trashing your previous employer in front of your prospective employer. 
Tip 2 : Revise all the technologies you have worked on, understand on a simple fundamental level on why something works. 
Tip 3 : Always prepare insightful questions that you can only ask upper management (CTO, VP Engineering)