Amazon Software Development Engineer SDE I interview questions

Good competitive questions. I have given 2 rounds in which DSA was asked. One Stack question based on next greater element another was a graph question. I did both the questions.

Count the number of islands in a Boolean matrix. Then he asked another puzzle :- Given 4 pages and written with x, y, 1, 2 and I have to make the minimum flips to make the pair(y, 2). (Very confusing puzzle).Then he asked a puzzle. That was like if I have boarding passes of a person without date and time and only with source and destination. If I shuffle the cards, Is it possible to tell the first initial source. I said no without time and date it was not possible.