P&C q9

[Saumyojit]

Which interpretation is correct.
Don't tell whole solution

First choosing one column then targeting not all but some of the lower ones, then moving to another column out of two then targeting not all but some of the lower ones, then last column targeting lower ones

Then targeting the remaining disks left in the same way.



Another interpretation
Choosing one column then targeting all Disks of that column until all disks are finished shooting (lower to higher), then
Another column out of two same process, then last column.
Or
Both Are Correct?

Am I able to explain my Confusion?

 

[Dr.Peterson]

Neither accurately describes all valid orders of shooting. You don't have to shoot all of one column before any other. (You may mean the right thing by your first description, but your words are far less clear than the problem itself.

The only requirement is that, for example, if we name the first column ABCDE, E must be before D, and so on. Disks from other columns may be shot in between.

Calling the others FGH and IJ, a sample valid order would be HJIEGDCFBA.

 

[Saumyojit]

How to arrange such that I make sure the lower ones are always first then the higher ones of their respective column

 

[Dr.Peterson]

There are probably several ways to do that; what thoughts have you had?

I'll give you one big hint: In the process of choosing an order to shoot, you never really have a choice about which disk in a given column to shoot. Once you've chosen a column, you are required to shoot the lowest one remaining. So it really comes down to choosing the order of columns.