1x
Recursion & Backtracking

Sudoku Solver

Step 1 of 6

A constraint satisfaction problem solved using a depth-first search through the space of possible digit placements.

The Three Golden Rules

A number (1-9) can only be placed if it is not already present in: 1) The current row, 2) The current column, 3) The 3×3 subgrid (box).

5
3
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7
1
2
4
Testing valid digits for empty cell