Consider an empty stack of integers. Let the numbers 1, 2, 3, 4, 5, 6 be pushed on to this stack only in the order

Q. Consider an empty stack of integers. Let the numbers 1, 2, 3, 4, 5, 6 be pushed on to this stack only in the order they appeared from left to right. Let S indicates a push and X indicates a pop operation. Can they be outputted in to the order 325641 and order 154623 ?

(Hint. SSSSSSXXXXXX outputs 654321)

Answer :-

SSSXXSSXSXXX outputs 325641.

154623 cannot be output as 2 is pushed much before 3 so can appear only after 3 in output.