Pergunta de entrevista da empresa Microsoft

first : online test has some problem solving(brackets and how to make it balanced , debug printed code, other easy one ) and multi choice machine learning . second : 3 interviews with three of different teams the interview level was [easy - mid] - given stack find the minimum when I need with allowed to pop or push anytime - decode string - given list of n number every num <= n , every num occurred at most 2 times find repeated num without using any other array.