Uber Software Engineer/Developer interview questions

The process was smooth, I only cleared the first stage so the asked for two medium level coding questions. Any language was fine by the interviewer. Interviewer was very friendly and helped with hints as well.

3 rounds 1st DSA I was asked a question on graph and I needed to find the shortest path between two prime number such as by changing any no. By one digit the another no. I get should be prime too. So how long will it take to reach the 1st 4 digit no. To 2nd no.