Cat Sudoku Level 220 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 220 Strategy
Expert Level 220 uses a 9x9 board with 9 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 220 Solution
Solution cells: R1C1, R2C7, R3C2, R4C5, R5C9, R6C3, R7C8, R8C6, R9C4.