Proteus Digital Health Senior Java Developer/Designer, Platform Services interview questions

First telephonic screen with principal architect then after one week they called for in person interview. It almost take full day.. between every 45 min -1 hr, one interviewer(including head HR, VP,Dev manager,principal architect, dev lead, production support lead, developer almost 10-12 people including QA tester). All of them will ask algorithm/Design questions to solve along with white boarding including QA tester. This is the one of the worst interview experience I had seen during my 12 years career. I believe they are collecting just idea about their system issues from candidates to just call them for interview and does not have intention to hire them at all. They are thinking this way they can implementing their own system issue. If am going to received offer from them I am going to decline it for sure.