Shield AI C++ Engineer interview questions

TLDR: Fun technical challenges, drawn out process, no intent to hire. Interview process: 1 hour Hiring Manager interview. 2 hour Technical Challenge. 4 hour take home C++ task. 1 hour presentation of C++ task to multiple team members. 1 hour Technical Challenge. 1 hour "Teamwork" interview. My "final round" was scheduled for Wednesday however I noticed they had already re-listed the position in LinkedIn before my final round. I really doubt they had any intent to hire - I think they're interviewing to pretend they're growing. I pulled out before the onsite. The communication was very poor - they ghosted me before coming back from the dead and offering a further interview. I also asked for feedback after the rejection and they ignored me. The technical challenges were very fun and difficult, so that was a positive. They also demand an NDA, however I refused to sign it.