Question

If the sequence of operation - push(1), push(2), pop, push(1), push(2), pop, pop, pop, push(2), pop are performed on stack, the sequence of popped out values are:
1. 2,2,1,1,2
2. 2,2,2,1,1
3. 2,2,1,2,2
4. 2,2,1,2,1

Answer 1

Correct Answer - Option 1 : 2,2,1,1,2

The correct answer is 2,2,1,1,2.

The pop sequence can be seen from the following table:

Operation	Stack	Pop
Push 1	1
Push 2	1, 2
Pop	1	2
Push 1	1, 1
Push 2	1, 1, 2
Pop	1, 1	2,2
Pop	1	2,2,1
Pop	Empty	2,2,1,1
Push 2	2
Pop	Empty	2,2,1,1,2