TikTok Intern - Software Engineer interview questions

one on one virtual interview. started with simple introduction then solving leetcode problem through hackerank platform. difference might be based on interviewer. my first round experience is very good, interviewer was super kind and very helpful. giving me a lot of advice and willing to share his thoughts. second round was less enjoyable, the interviewer didn't show up at the scheduled time, even I sent a mail to the hiring team. Got the mail back one week later and scheduled another time. Process is almost the same as the first time, however, I could feel the vibe is not right between us.