ISRO | ISRO CS 2008 | Question 67
Stack A has the entries a, b, c (with a on top). Stack B is empty. An entry popped out of stack A can be printed immediately or pushed to stack B. An entry popped out of the stack B can be only be printed. In this arrangement, which of the following permutations of a, b, c are not possible?
(A) b a c
(B) b c a
(C) c a b
(D) a b c
Option (A): Pop a from stack A Push a to stack B Print b Print a from stack B Print c from stack A Order = b a c Option (B): Pop a from stack A Push a to stack B Print b from stack A Print c from stack A Print a from stack A Order = b c a Option (C): Pop a from stack A Push a to stack B Pop b from stack A Push b to stack B Print c from stack A Now, printing a will not be possible.
So, option (C) is incorrect.
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