tenka1_2018_C

https://gyazo.com/ded3891efa2ce77c3e1abc6275cdbce5

Thoughts.

Same no matter how you do it when you have two.

When there are three, do you bring the largest value to the middle or the smallest value to the middle? Either one is the same.

When 4

Maximum and minimum values should not be placed on the edge

After that, zigzagging is OK.

in general

When the number of four is monotonically increasing, it is always better to swap the middle two and zigzag

For zigzag piles other than the edge, swapping them around does not change the result.

How should we think about the edges...

Always better to swap if the end is on the smaller side of the zigzag and lower than the valley with the zigzag

If you have an even number of pieces, just split them in half, large and small, and end up with two on the boundary.

If you have an odd number of pieces, do you want more large or more small...

You want to try a small row to make sure, if different, try both.

The above considerations yield an answer in sorted linear order.

Official Explanation

Roughly the same feeling

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