Salesforce Member of Technical Staff(MTS) interview questions

Its was completely focused on DSA and there was no prior communication about the interview process though i was not in touch was able to solve few of them .

I have been interviewd at salesforce 4 times since past year let me share my worst experience with any organization - Role - 1- TAM analyst(tableau)- Give 2 round tech and manager got rejected within 2 days. 2- MTS(data engineer)- Give 4 rounds of interview in just 2 days straight rejection without any feedback of such long process. 3-AMTS- Interview was scheduled just before one day before the interview I was informed that the position is filled. 4- data consultant- First technical round receive a call that I goot selected for second round which was such a long case study with ppt took great effort to complete it in just 4 days .After that ghosted by HR for 2 weeks and receive a general workday rejection . The thing I can't understand why to interview again and again the same candidate when you can't provide the feedback and waste time till the last round if you already think the candidate is not suitable in first round such a waste of time and efforts.