Cat Sudoku Level 257 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 257 Strategy
Master Level 257 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 257 Solution
Solution cells: R1C9, R2C2, R3C5, R4C10, R5C6, R6C1, R7C4, R8C7, R9C3, R10C8.