Dog Sudoku Level 21 Hint
Find a bone with only two or three available neighboring cells, then test those cells against the row count, column count, and no-touch rule.
Dog Sudoku Level 21 Strategy
Easy Level 21 uses a 6x6 board with 5 bones. Use the row and column dog counts first, then resolve bones with limited neighboring cells.
Dog Sudoku Level 21 Solution
Solution dog cells: R2C1, R2C5, R4C1, R5C6, R6C2.