+17 votes
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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
asked in DS
edited | 851 views

## 1 Answer

+22 votes
Best answer
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) $80$

answered by Boss (31.3k points)
edited by
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Content of stack at end of evaluation should be empty?

+10 votes
1 answer
1
+20 votes
2 answers
2
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