"Sandwich Sudoku" is a variation of the classic Sudoku puzzle that adds an extra layer of complexity through the use of "sandwich clues." This variation provides a new solving challenge by incorporating sandwich clues that provide information about the sum of numbers in a certain row or column, sandwiched between the highest and lowest numbers. Regular Sudoku Rules: The standard Sudoku rules apply. You need to fill a 9x9 grid with digits from 1 to 9, ensuring that each row, column, and 3x3 subgrid (box) contains all the digits without repetition. Sandwich Clues: In addition to the regular Sudoku rules, there are sandwich clues provided around the grid. These clues indicate the sum of the digits between the highest and lowest digits in the corresponding row or column. Number Range: The numbers used in the sandwich clues can only be between 1 and 9, inclusive. The sum indicated by the sandwich clue should match the sum of the numbers between the highest and lowest numbers in the row or column. Logical Deduction: The sandwich clues add a new layer of logical deduction. You need to consider the sandwich clues while solving the regular Sudoku constraints to determine the placement of numbers. For example, if a sandwich clue of "10" is given at the left side of a row, it means that the digits between the highest and lowest numbers in that row should sum up to 10. This provides additional information that can help you deduce the possible values in that row. Here's a simple example of a "Sandwich Sudoku" puzzle: In this example, the sandwich clue "15" at the top row means that the digits between the highest and lowest numbers in that row should sum up to 15. "Sandwich Sudoku" adds an interesting twist to the classic puzzle, challenging solvers to consider both the regular Sudoku rules and the additional constraints imposed by the sandwich clues. It can provide a refreshing challenge for Sudoku enthusiasts looking for something new.