Cat Sudoku Level 81 Hint
Find a colored region with only a few safe cells, then compare those cells against the row and column limits.
Cat Sudoku Level 81 Strategy
Medium Level 81 uses a 7x7 board with 7 colored regions. It starts with 2 fixed cats to anchor the solve. Work from the tightest rows and regions before placing a cat.
Cat Sudoku Level 81 Solution
Solution cells: R1C5, R2C7, R3C3, R4C6, R5C1, R6C4, R7C2.