Double Dutch Sudoku Advent (19) - 1~9 vs. Clocks
(Published on 19. December 2014, 12:00 by Richard)
Eisbär (Arvid) and I have created a fresh sudoku advent calendar in which we combine a well known variant with a relatively unknown variant every day. Combining variants leads to interesting and surprising new solving techniques.
Logically solvable
All puzzles can be solved completely logically although the logic is sometimes well hidden and is inherent to the combination of restrictions that the different types offer. For that reason we have written some solving hints for most of the puzzles, published in a very tiny font. If you want to read the hints, simply copy these in a text editor and enlarge the font size.
1~9
Place the digits from 1 to 9 in every row, column and 3x3-block. Clues outside the grid are the sum of the digit(s) placed between 1 and 9 in the corresponding row or column.
Clocks
There are some digital clocks placed in the grid. All clocks should display a valid time in 24-hour format (HH:MM); i.e. a clock can display 23:58 but not 32:85 etc.
Solving hints
Start with R5. R5C16 = pair {12}; 3 in R5C2 or R5C7.
Sum-clue in that row is 18, so minimal 3 cells between 1 and 9. :=> 9 not in R5C2 and R5C7 since that would force a 1 immediately in front of the 9 with a sum of 0. 9 also not in R5C9 since there would be either 2 or 7 cells between 1 and 9. :=> 9 in R5 in R5C5.
R5C1 = 1; R5C6 = 2; R5C7 = 3; R5C38 = pair {45}.
9 in block top middle not in R1C4 since one of R1C5 or R2C4 has to be 1 and none of the sums in R1 or C4 is 0. Also no 9 in R1C6, R2C6 or R3C4. :=> R3C6 = 9
R6C6 = 1, R4C6 = 4
9 in R6 in R6C89
9 in block bottom middle in R7C4
Solution code: Both main diagonals. First from top left to bottom right, then top right to bottom left.
Comments
on 11. April 2022, 00:50 by Nick Smirnov
Penpa:
https://tinyurl.com/yboywlba
on 5. June 2017, 12:25 by Saskia
schoen!
