Intel Corporation Software Developer interview questions

It started with an hr interview, than I had 3 hours technical interview, which splitted to 1 hour for each interview, each one was a diffrent interviewer, 1 question was about system design, 2nd was leet code sytle question, and last was understanding existing code and implementing change

2 people introducing themselves, asking about you and the role and the process. Interview held face to face in their office, there's a white board and paper and pens. Question was to implement a phone book. So given a name, you want to find the number or if the name does not exist. Explain your thought process.