VMware Staff Engineer interview questions

First Round was Design round. Had good interaction and discussion on the design. Second Round was coding. I asked interviewer if he wants me to solve with best time complexity or any. he said you can solve by any method. I choose to solve brute force way. All test cases ran successfully. He said it will take more time complexity so solve in O(n). I though if he wants in O(n) he should have told me earlier when I asked him. Still I solved the problem and all his test cases ran successfully. But still that guy was not satisfied. He said that he will see my problem later on and will think on that. I mean what is this ??? He is not able to find any prob at the moment then he will try himself offline and then he will give feedback . Then they rejected me. I am really disappointed with this.

There was no clarity in the position I was being hired for. Had applied for Staff engineer and not sure why was being considered for senior software engineer. The rounds went fine, but it took them 7 rounds of interviews to be ruled out for not having same technical backgrounds.