Solutions to 1st Code Road – Part 2/3

Puzzle 3 – Sum Thing Happened

cd1ans4a

The Killer Sudoku was probably the hardest puzzle in Code Road. First off lets solve the sudoku:

cd1ans4bThe given 0, 1 and 2 restricts the possibly of the 8-cage to 0, 1, 3 and 4. This further forces the content of the 12-cage to 5 and 7. More contents of 2-cell cages can be determined but not yet placed in the centre-bottom nonet. The 3-cell cage adding to 4 has to contain 0, 1 and 3 only.

cd1and4c

The 15-cage has be to maximally filled with 7 and 8, so the placement on the 12-cage can be determined. The central horizontal row can now be filled using the content of the 8-cage in the central-right hand side nonet. The 22-cage can be filled with either 6, 8, 8 or 7, 7, 8 – but since the determined 1, 7 filling the 8-cage – leaves only one possible placement of 6, 8 and 8.

cd1ans4d

More progress can be made looking at the 3rd column, the top 6-cage has to contain 1 and 5. The bottom-left nonet can also be marked. Using basic sudoku rules and the key placements in the vertical 9-cage and the 17-cage, the entire left hand side of the puzzle can be fully mapped.

cd1ans4e

The 7th row can be mapped using the remaining 3 numbers, the 1 has to go to the 14-cage to satisfy the 8-cage. The 7-cage in the top right nonet is left with 3 and 4. The 0 forces the neighbouring cell to be a 5, which makes more progress in the top left corner. From here, try to remind yourself to revisit the sudoku rules. This should open the 6th column and clear the top-centre nonet.

The last 10 or so cells are now a piece of cake.

cd1ans4fcr1p3b

After you’ve solved the Killer Sudoku using numbers 0-8. The shaded squares read out a date. Which was 18/11/1307. According to the Swiss folklore, it is the day that William Tell famously shot an apple from his son’s head. The 11 letter answer is WILLIAMTELL.

Construction Notes: Because the solution date had a zero, a sudoku wasn’t possible so I originally have in mind, a Number Crossword. Think a crossword where the clues are something like [23 Across: 392+956], [13 Down: Number of rings in the Olympics logo + Days in July], [6 Across: A prime number] etc. A run of eight digits would be shaded to reveal the date of 18/11/1307.

When I opened up Excel, drew a grid and start filling in entries I thought, “Man. This is boring.” It would be a crime to put my own readers to that much boredom so I quickly scrapped the idea for something else.

The Killer Sudoku was actually one of many puzzles from my puzzle shed (a place where unused puzzles made with no clear intention slowly pile up). The original puzzle was 1-9 but since the date contained a zero every digit was subtracted by 1 and every cage was subtracted by the number of cells it contained.

Test solved it 3 times because puzzles from my puzzle shed aren’t thoroughly checked like ones I write for planned occasions. The puzzle works. Hooray. Into Code Road it went.

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