## Saturday, August 27, 2011

### USPC 2011

Well, it just wouldn't be a USPC without a roundup. (see also USPC 2010, USPC 2009, USPC 2008, USPC 2007)

1. Battleships
Ugh, I spent too much time running around in circles, trying to figure out where to place the cruisers. Somehow I got it into my head that I needed one in the leftmost column, because they couldn't fit in the rightmost two columns. I ended up printing out this page three times, making the same deductions before finally solving it.

2. Sudoku
Ok going at first, but then I got stuck, so I did a little bit of guessing and worked it out. Slower than I like, but not as bad as Battleships.

3. Crossied Countries
No problems here.

4. Barn Storm
For some reason, I thought had one less difference than I had found and wasted a few minutes trying to find an 11th!

5. Easy as ABCD
More information than I was used to (compared to the Mensa Blue Book), but also larger than the ones I had practiced on. After a few initial deductions, I did a little bit of guessing and got it completed.

6. Times Like These
Tried fiddling with the first row for a bit, and then looked at the third row. The 7 there needs to be either the tens digit in the product or the ones digit of one of the multiplicands. Some quick checking yielded 2x6x7=84. Cross-referencing the columns, I got the placements, filled in the first column, and then the rest.

7. Masyu
Did as much logic stuff as I could, most notably the top-left and bottom-left corners, then did some pencilwork for filling in the rest.

8. Square Count
More or less ok, but missed 2 of the A=2 diagonal squares, so only partial credit.

9. Crack It On
Worked on breaking the right side first, since it required at least three words beginning with the same letter. Some trial and error with the remaining words got the left side.

10. Flash Cards 1
Mostly trial and error, working with different digits for the single in the product.

11. Flash Cards 2
Quickly realized that the denominator needed to factor into two single digits for the flip, and only a few possibilities existed among the digits (32, 36, 27, 63, no right side up 8 or 9 for 72 to work).

12. Takeout
Pretty straightforward.

13. Corral
Not bad, but slower than usual, esp. trying to figure out whether the central mass in the 7th row needed to break out right or left.

14. Blocks (solved after time)
Easy deduction of the square and 4-long piece. Then a dead-end in the bottom-right yielded one more. Worked out a Hamiltonian path in the middle-left that seemed likely, and made placements from there.

15. Hex Words
Still working on it.

16. Word Connection (solved after time)
The two "P"s and two "T"s were good for fixing September/April and October/August, respectively, and then just needed to fit the rest in.

17. Hopper (solved after time)
Not as bad as Tom Snyder's practice. The second 1 didn't leave a lot of choices, and I stopped trying to make it too compact, since it needed to be a unique fit for 8x8.

18. Corral Crates
Still working on it. Doesn't seem too bad, if larger than Palmer's.

19. Kaku Rogue
Got everything but the top-left and lower-right corners. Not sure of a good way to go about it except to try different numbers until one works. The first time for me that checking column and row sums worked: in this case, for the singleton connecting squares.

20. Jumping Crossword
Still working on it.

21. Hungarian Tapa
Still working on it.

22. Dynasty Sudoku (solved after time)
A long time making deductions, then guessing, only to get a solution that is only slightly wrong with two transpositions and violating the single-connected-space constraint.

Potential points: 170
Expected points: 160 (partial credit on 5.)

Fingers crossed for a good ranking this year.

EDIT: Hex Words isn't bad, once you realize that intersecting words on a hex grid need to have valid words along all three axes. This forces JUDO into the upper-left, and using an efficient packing heuristic for the rest works pretty well.

Corral Crates also wasn't too bad, though I messed up early and had a contradiction. Much of the strategy is the same as for Corral: since each crate cannot touch empty space diagonally, the really useful anti-checkerboard constraint still holds.

Kaku Rogue worked out with more guessing, but I need to check my answer -- Oops, didn't even see the second constraint on exactly one negative number per row and column. Good thing I didn't do this one, I guess!

EDIT 2: Looks like I did miss a 10th difference on Barn Storm, so my total score this year is 154.

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