Salesforce Software Engineer interview questions

Got email from HR to schedule phone interview. First round was a walk through the course work and resume. One coding question : Get remainder string after a sub string. Example: inputStr = "abcde" subStr = "cd" return = "e" Secound round was another technical round. The interviewer was not clear with his question. Max repeated character which occurs at a time first index.. Example: aabbaaa output: 4