Salesforce Software Engineer(Internship) interview questions

First round: 1) Possible Path from hackerrank 2) binary search question with ranges Second round: Introducing my self - What is HTML? - What is REST API? after this questions I solved two hackerrank questions 1) Unique characters in a string.(HashMap) 2) Dynamic programming with strings third round: the same type of questions as second round but talking more about a project that I have worked on. after that a hackerrank session : Implementing a new data structure with given methods.

Sort An array of "R","G","B" in one pass