Last Free Cell
This is a simple strategy that relies on identifying units where only one cell is empty.
- The Sudoku grid consists of rows, columns, and 3×3 blocks. We will refer to these parts (rows, columns, and blocks) as “units.”
- To find the cell with the last remaining number, check which numbers are already present in the row, column, and block.
- Therefore, if there is only one free cell left in a unit, it is easy to determine which number from 1 to 9 is missing.
