This year's US sudoku qualifier again featured two parts: one with regular sudoku and "classic" variations, and another with less common variations and new styles. This week I will share two of the harder "classic" variations that I wrote for the test, an Irregular Sudoku and a Nonconsecutive Sudoku.
The Irregular's theme developed out of the central cage geometry, extending the pattern with givens when the the regions could no longer follow. It has a bunch of stall points, and requires several different strategies to complete, so it certainly deserves the high point value it received.
The Nonconsecutive built off a less common symmetry for sudoku but with a choice of positions that really works well with a nonconsecutive puzzle to maximize interactions with adjacent cells at the start. It too has a couple transitions in approach which makes it a longer solve than usual.
Rules: Place a single digit from 1 to 9 into each cell so that no digit repeats in any row, column, or bold region.
Rules: Place a single digit from 1 to 9 into each cell so that no digit repeats in any row, column, or bold region. Additionally, no pair of consecutive digits can be placed in vertically or horizontally adjacent cells.