ITPEC IP April 2020 Question 8
ITPEC IP April 2020 — Question 8 of 100
The final stack contains 1 at the bottom and 2 at the top. Initially it is 1,2,2,3,4 from bottom to top. Operation 1 replaces 3 and 4 with 7; operation 2 pushes 3. Operation 3 replaces 2,7,3 with their average 4. Operation 4 replaces 2 and 4 with their absolute difference 2.
Answer (b)
Why not others:
- the bottom 1 is never removed
- after each operation, removed boxes are replaced by only one new box, leaving exactly two boxes at the end
Key rule: A stack is LIFO, so every removal and insertion occurs at the top.
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