Logic Masters Deutschland e.V.

The number 7 is often considered to be lucky, but in this unlucky sandwich sudoku all of the 7s have been replaced.

Unlucky Sandwich Sudoku Rules

This puzzle follows standard sudoku and sandwich sudoku rules (referenced below), with one major exception:

All of the 7s that would appear in a standard sudoku grid have been replaced by each of the digits 1 through 9. The replacement digits are allowed to break the standard sudoku uniqueness rules. (Yes, one of the 7s was even "replaced" by a 7, so there is a single 7 in the final grid.)

The replacement digits are reflected in the sandwich sums but cannot be used as crust digits.

Given digits are highlighted in blue if and only if they are replacement digits. (That is to say, unhighlighted givens are not replacements.)

Standard Sudoku Rules

Each cell should be filled with one of the digits 1 through 9. Digits may not repeat within any row, column, or outlined 3x3 subgrid.

Sandwich Sudoku Rules

Each number outside the grid indicates a "sandwich sum" for its adjacent row or column. A sandwich is formed within a row or column by its 1 and 9 ("crust digits"), and the sum contains all of the digits between them.

Links and Puzzle

• Play on SudokuPad