ISRO-DEC2017-47

Question

Which of the following permutation can be obtained in the same order using a stack assuming that
input is the sequence $5,6,7,8,9$ in that order?

• A. $7,8,9,5,6$
• B. $5,9,6,7,8$
• C. $7,8,9,6,5$
• D. $9,8,7,5,6$

Comments

C is answer

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C is the option.....

simply push in given sequence and pop according to option given.... ...

Answer 1

Option A can't be true because 6 cannot be popped after 5 when 5 is coming before 6.

Option B can't be true too because 6 can't be popped before 7 or 8.

Option C is possible:
Push 5
Push 6
Push 7        Pop 7
Push 8        Pop 8
Push 9        Pop 9
                    Pop 6
                    Pop 5

Option D can't be true because 5 is getting popped before 6.