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Suppose a stack implementation supports, in addition to PUSH and POP, an operation REVERSE, which reverses the order of the elements on the stack.

1. To implement a queue using the above stack implementation, show how to implement ENQUEUE using a single operation and DEQUEUE using a sequence of $3$ operations.
2. The following post fix expression, containing single digit operands and arithmetic operators $+$ and $*$, is evaluated using a stack.
$5 \ 2 * 3 \ 4 + 5 \ 2 * * +$
Show the contents of the stack
1. After evaluating $5 \ 2 * 3 \ 4 +$
2. After evaluating $5 \ 2 * 3 \ 4 + 5 \ 2$
3. At the end of evaluation
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1. For enqueue push operation is sufficient
For dequeue operation do the following
-reverse, pop, reverse

2. Contents of stack from top to bottom:

i) $7 \ 10$
ii) $2 \ 5 \ 7 \ 10$
ii) $80$

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Content of stack at end of evaluation should be empty?
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for dequeue it should be reverse and pop are sufficient.
+1

For dequeue reverse and pop are not sufficient because we might have popped only one element and would need to push later on. If we don't restore the order the the elements will be jumbled.