Cat Sudoku Level 172 Hint
Find a colored region with only a few safe cells, then compare those cells against the row and column limits.
Cat Sudoku Level 172 Strategy
Hard Level 172 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 172 Solution
Solution cells: R1C3, R2C9, R3C7, R4C1, R5C6, R6C4, R7C8, R8C5, R9C2.