To sell online in some marketplaces and for retail outlets every product needs to be labelled with a GTIN or EAN number. For most, this comprises a 13 digit EAN13 barcode number. Getting hold of an EAN number used to be quite straightforward, you’d simply buy a block of a set amount from some dealer […]

Now we’ve found the only way to solve complex Sudoku puzzles is suck it and see, we need a method for displaying and modifying the grid. So let’s start with displaying the grid. Rather than work out the formula’s for cell borders I thought, “Hell I only need to do this once so let’s define […]

Last time we developed the algorithms to eliminate duplicates from the grid and then search for values where one number is unique in the group, row or col. This worked for a variety of puzzles but we came a cropper on the last one, namely: You can see in this puzzle that the algorithm has […]

Last time we worked on alogrithm to solve Sudoko puzzles, see Sudoku Solver PHP Part 1. This worked for easy puzzles but when a more complex grid was entered the code could not solve it. A further algorithm is needed. The way the algorithm worked was to assume every square (except those given starting numbers) […]