sudokUI › Sudoku techniques › Brute Force
Brute Force in sudoku
No pattern at all: digits are tried in the empty cells one after another, backing up at every dead end, until the whole grid is filled.
Why it works
A grid filled without breaking a rule is a solution, and a proper puzzle has exactly one. A digit from that solution is placed in an empty cell, with no reasoning a player could follow.
How to spot it
There is nothing to spot: if you must guess by hand, choose a bivalue cell and note where the guess began.
The solver uses this on the hardest puzzles. It has no pattern to spot, so it is not offered in practice.
In a puzzle's rating
Each time the solver needs Brute Force, the puzzle's difficulty rating grows by 10000. Its class is Extreme. It is needed in fewer than 1 in 5,500,000 puzzles that sudokUI generates. How the rating works.
More last resort
Exocet · Double Exocet · Pattern Overlay · Forcing Chain · Digit Forcing Chain · Nishio Forcing Chain · Cell Forcing Chain · Unit Forcing Chain · Forcing Net