Cat Sudoku Level 231 Hint
Look for a region whose legal cells are squeezed by two or more neighboring rows. High-level puzzles often move through exclusion, not obvious singles.
Cat Sudoku Level 231 Strategy
Master Level 231 uses a 10x10 board with 10 colored regions. It starts with 1 fixed cats to anchor the solve. Work from the tightest rows and regions before placing a cat.
Cat Sudoku Level 231 Solution
Solution cells: R1C8, R2C6, R3C3, R4C9, R5C7, R6C4, R7C2, R8C10, R9C5, R10C1.