# Happy birthday, Bernardo - Colombian Sudoku

Bernardo, hb!!! This is a Colombian sudoku made in honor of my friend Bernardo Recamán, for his birthday. Complete the sudoku on the left so that each row, column, 3x3 square, and cell of the same color contains the numbers from 1 to 9. The dots indicate how many numbers in the row or column of the grid on the right match the solved sudoku on the left. This Colombian sudoku is special because there is only one correct number for each row and column. Happy birthday!!!

• The dots indicate how many numbers in the row or column of the grid on the right match the solved sudoku on the left. I am unclear on how the dots indicate this. Can you give an example? Commented Aug 6 at 18:12
• @GentlePurpleRain One number from each row/column will match because there is one dot next to each row and each column Commented Aug 6 at 18:33
• @GentlePurpleRain If there were 3 dots, then 3 of the numbers in the table would match the Sudoku. This is different because, with one dot in each row and column, only one number should match. Look at my puzzles... Commented Aug 6 at 19:58
• The solved sudoku contains rows and columns with repeated numbers. So it's not really a "solved" sudoku, right? Commented Aug 7 at 10:49

Happy birthday Bernardo! Here's the solution:

I'm embarrassed to admit I didn't realise the numbers spelt out 'hb' until after solving :P

Step by step:

1.

To start, we can highlight the one number that matches - the 9 bottom right - as correct by bold and underlining it. As this sudoku only has 1 number that matches, we can also then cross out the entire rest of that row and column.

We can now highlight all the numbers that aren't possible in the right hand grid, in situation such as the same number in the same row, column, box or colour as that cell in the left hand grid. We can also cross out any number where the cell is already filled with a different number.

Consider the 8s on the left hand grid. The only yellow box where an 8 can go is top middle. We can place this - and mark it as correct on the right grid, updating the new impossible cells too.

Now in the middle box, the bottom cell can't be a 5, and can't be a 7 as the colour 7 has been taken, so it must be a 2. Updating accordingly:

Continuing in the middle box, the top cell cannot be a 5 as that colour is taken, so we can complete the box.

Now looking at the yellow cells, there is a 4/9 pair in the remaining bottom 2. Not only is this a pair in a row, it is also a pair in a colour which removes a lot of candidates elsewhere and leaves only one place for a 5 in the second column, at the bottom.

This then leaves only one place for a 5 in the 8th row as well. Updating everything:

There is now only one place for a 5 in the middle left box - which is a match.
This means the 8th row now only has one possibility for the correct number, the 4 in column 2.

This solves the 4/9 pair and updates a lot of the right grid. It also means that column 2 can be solved, as there is an 8/9 pair remaining and one of the cells can no longer be a 9:

In the 7th row now, the 4 in the right grid can't be correct, so the 3 must be correct.

In the middle right box, there is a 4/6/9 triple at the top, which means the bottom right cell must be a 7. This solves a 6/7 pair in the last column, placing a 6, and solves a 2/7 pair in the middle right box, placing a 2 and also placing a 7 as the final yellow.

The middle row's correct number now has a 4/7 pair in the left middle box, meaning the correct number must be the 7. This solves the middle row completely.

The 6th and 8th row can now both also be completed. The bottom right cell must be an 8 due to a 4/9 pair in the same box, placing a 7 in the same box too. This 7 happens to be a match.

This leaves just the 2 in the 3rd row as the matching number, and the 7 in the first row - and the right hand grid is now complete!

Now to finish off the left hand side. The 6th column can be completed, which in turn completes the right middle box. The right hand column can be completed, followed by the blue squares. The bottom right box can now be completed.

Finally, you can complete the grid. To start, the greens can be solved - followed by the pinks. This then solves the bottom left box, the bottom middle box, leaving this:

The top left green must be a 6, and as the top left cell cannot be 8, everything falls into place, giving the solution: