This page generates solutions for the Sudoku puzzle featured in The Times and elsewhere. Find The Times' version here.
I'll do ones for "Killer" and "Kenken" when someone can suggest an easy user interface for the "shapes".
Please enter the supplied numbers in the grid below and press the button to get the answer.
If there are several solutions, the first one found is displayed.
The method is to iterate over each row, column and 3x3 box to insert values which can only go in the square and then to insert values for which other positions in the same row, column or box are not possible.
If that can do no more, heuristic searches are done by guessing one of several possibilities for one square to see if a solution can be found with that, possibly repeating recursively.
For a blow-by-blow account of the solution steps, select the checkbox.