Day 50
Day 50: Sudoku Solver
50/60 Days
Day 50: Sudoku Solver #
Welcome to Day 50 of our 60 Days of Coding Algorithm Challenge! Today, we’ll tackle the Sudoku Solver problem, another classic application of backtracking algorithms.
What is Sudoku? #
Sudoku is a logic-based number-placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, row, and 3×3 sub-grid contains all digits from 1 to 9 without repetition.
Understanding the Problem #
- We have a 9×9 grid, partially filled with digits from 1 to 9.
- Empty cells are represented by 0 or ‘.’.
- We need to fill all empty cells following Sudoku rules.
- A valid Sudoku solution must satisfy:
- Each row contains digits 1-9 without repetition.
- Each column contains digits 1-9 without repetition.
- Each of the nine 3×3 sub-grids contains digits 1-9 without repetition.
Backtracking Approach #
We’ll use a backtracking approach to solve this problem:
- Find an empty cell.
- Try placing digits 1-9 in this cell.
- Check if the digit is valid in the current cell.
- If valid, recursively try to fill the rest of the grid.
- If the recursive call is successful, return true.
- If not successful, backtrack and try the next …
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