Problem 8 · 2024 Math Kangaroo
Medium
Logic & Word Problems
work-backwardcasework
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Answer: C
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Hint 1 of 2
A box can be moved only when nothing sits on it, so the order boxes become free is fixed by the starting picture.
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Hint 2 of 2
For each tower, check whether a box ends up under another box that was still trapped when it had to be placed; that ordering conflict makes a tower impossible.
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Approach: check the forced unloading order against each tower
- From the start, only the top boxes are free; a box can be placed under another only if that other box was already moved.
- Read each target tower from the bottom up and see whether every box placed below another could have been freed and set down before the box on top of it.
- Tower C requires putting a box beneath one that was still pinned at that moment, which the rules forbid.
- So the worker cannot build tower C.
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