GC2KCWV - HC Starry Sudoku
By: sandlanders
1. Here is the puzzle.
When we camp at Hartman Creek State Park, we sit around our fire as the campground settles down for the night. It gets quieter. It gets darker. At some point, as the fire dwindles to orange coals, we decide it’s time to turn in, so we head to the shower building one more time. There are electric lights on in the building as we approach the clearing, but other than that, we see only the orange glow from the campfires, the hissing yellow-white from the camp lanterns, and the occasional guiding beam of a flashlight or two.
Then we look up. There are stars everywhere!
They are so bright and close! And they are all ours...
Below is a simple sudoku puzzle. There's nothing very hard about it... You don't even have to be a Sudoku Star to figure this one out. However, at some point in your solve, you will have to make a decision. If you were doing a normal sudoku puzzle, you would say, “This isn’t solveable!” But remember: this is a puzzle for a geocache. It’s not a normal sudoku. You are not going for a solve but for the coordinates. Use your geosense. Think about what you need to do. Make a decision. Once you have done that, you will have the numbers you need AND you will have solved the sudoku puzzle in the process! After you have filled in the grid, take the numbers you have put in the boxes containing letters, and substitute them for the corresponding letters to find the final coordinates here:
N 44 AB.CDE W 089 FG.HJK
2. Solve the Sudoku puzzle.
Here are links to sites that will help you solve this puzzle.
WikiHow - How to solve a Sudoku
Sudoku Essentials
Let's start by correcting an error in the cache description:
"...However, at some point in your solve, you will have to make a decision. If you were doing a normal sudoku puzzle, you would say, “This isn’t solveable!”..."
This statement is not accurate. Every Sudoku has a solution, one solution. When we reach the point in the puzzle that appears to be "unsolveable", we will tell you about the Sudoku rule that will resolve the problem. You will not need to guess or use geosense to solve this Sudoku puzzle.
The most important rule for Sudoku is that each number is used one time, and only one time in each Row, Column, and Square of boxes.
For this Sudoku, you will use the numbers 1 - 9.
Evaluate the given numbers, and you will see that the easiest number to solve is 1, so start by solving the 1's.
The next section that's interesting is Row 4. Only two numbers remain, 7 and 8, so solve this row. Since it is not yet possible to identify which number goes where, place both numbers in each box. These are the 'only' numbers that can be placed in these two boxes.
Since Square 6 only needs two number, 7 and 8, to be fully solved, that is the next section that should be looked at. Column 9 already has an 8; therefore the 7 will be placed in Row 5, Column 9. That leaves the 8, which will be placed in Row 6, Column 8.
Notice that there are already 2's in Columns 4 and 5, and Rows 4 and 6. That means the only place a 2 can be place in Column 6 is on Row 5.
There are already 3's in Columns 4 and 5, Squares 2 and 5, and Row 9. That means the only box in Column 6 where a 3 can be placed is Row 7.
Next you can solve Column 5, Rows 5 and 6, of Square 5. Since the numbers can only be 4 or 5, and there is already a 5 in Row 5 and a 4 in Row 6; for Square 5, the 4 must go in Row 5, and the 5 must go in Row 6.
Square 1 can be solved as follows. Box 2 must be a 2, because Rows 2 and 3, and Column 3 already have 2's. Box 8 must be a 5, because Column 3 and Row 2 already have 5's. Box 5 must be a 6, because Column 3 already has a 6.
Now we will look at the "Special Rule" that was mentioned earlier. Look at the block of squares that are highlighted with pink. Notice that all four squares have the numbers 7 and 8, and one square has the number 9. This appears to be an unsolvable loop. It is not. When this occurs, the box with the number 9 must be a 9.
Therefore, enter a 9 in Row 2, Column 6. Also, since Square 2, Box 6 must be a 9; then Square 2, Box 8 must be an 8. Furthermore, the following boxes can be solved. Row 2, Column 8 is a 4; Row 3, Column 8 is a 9; Row 9, Column 5 is a 9; and Row 9, Column 6 is an 8.
Square 1 has two unsolved numbers, 4 and 8. Since there is already a 4 in Row 2, the 4 must go in Row 3, Column 3 and the 8 must go in Row 2, Column 3. That means Row 2, Column 4 must be a 7; Row 4, Column 4 must be an 8; and Row 4, Column 6 must be a 7.
3. Identify the solved numbers.
A = 1
Therefore, the only remaining numbers that need to be solved for Column 5 are 8 and 9. Since there is no way to tell, yet, which boxes they belong in, place 8 - 9 in both boxes. No other numbers can go in these boxes in Column 5.
Now look at Row 5. The only number that has not been solved in Row 5 is the 9. Place 9 in Row 5, Column 1.
In Row 6, the only unsolved numbers are 3 and 4. Since there is already a 3 in Column 1, the 4 goes in Row 6, Column 1; and the 3 goes in Row 6, Column 2.
In Square 7, the 8 must go in Box 1, because there are already 8's in Column 2 and Row 8. The only unsolved numbers in Column 1 are 6 and 7. Since Row 8 already has a 7, the 6 will go in Column 1, Row 8; which means the 7 must go in Column 1, Row 3.
In Square 9, the 3 must go in Box 6; because there are already 3's in Rows 7 and 9 and in Column 8. The 6 must go in Box 3, because Column 8 already has a 6. The 2 must go in Box 2, because Rows 8 and 9 already have 2's. The 5 must go in Box 8, because there is already a 5 in Row 8. And the 7 must go in Box 5, because that is the only number left to complete Square 9.
For Row 7, the 4 must go in Column 2, because Square 7 already has a 5; and the 5 will go in Column 4, because that is the only unsolved box left in Row 7.
In Square 8, the 6 must go in box 7; because Column 6 already has a 6. That means box 9 must be either an 8 or a 9. This means that 7 must go in Row 9, Column 2. Which means that Row 8, Column 2 must be a 9.
Now we'll work on Square 3. Box 9 must be a 2, because Columns 7 and 8, and Row 2 already have 2's. Box 4 must be a 3, Because Columns 8 and 9, and Rows 1 and 3 already have 3's. Box 6 must be a 5, because that is the only unsolved number in Column 9. Box 7 must be a 6, because there is already a 6 in Column 8 and Row 1. Box 1 must be a 7, because that is the only unsolved number in Column 7. The only remaining unsolved numbers are 4 and 9. They should be placed in the remaining boxes.
In Square 2, Box 3 must be a 5, because Column 4 and Row 2 already have 5's.
Row 1, Column 3 must be a 9, because Column 4 already has a 9. Therefore, 4 must go in Row 1, Column 4. That leaves only 7 or 8 that can go in Row 2, Column 4; and 7,8, or 9 can go in Row 2, Column 6.
Square 1 has two unsolved numbers, 4 and 8. Since there is already a 4 in Row 2, the 4 must go in Row 3, Column 3 and the 8 must go in Row 2, Column 3. That means Row 2, Column 4 must be a 7; Row 4, Column 4 must be an 8; and Row 4, Column 6 must be a 7.
Highlight the labeled numbers, and make a list of the solutions.
B = 9
C = 6
D = 7
E = 9
F = 1
G = 2
H = 7
J = 1
K = 7
4. Put together the Solved Coordinates.
Here are the puzzle coordinates.
N 44 AB.CDE W 089 FG.HJK
Solved Coordinates:
N 44 19.679, W 089 12.717
5. Verify the Solved Coordinates.
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