46. Sudoku Solver

Hard

Topics

Helpful tools to learn & understand

Visualize LogicActive Simulator

Watch key transitions, pointers, and variables update step-by-step.

Open

Check Solutions

Read clean, documented implementations across multiple patterns.

View Code

Thinkpad (Draw & Note)

Sketch diagrams on an infinite canvas and draft notes directly inline.

Draw

Example 1:

Input:

board = [["5","3",".",".","7",".",".",".","."],["6",".",".","1","9","5",".",".","."],[ ".","9","8",".",".",".",".","6","."],["8",".",".",".","6",".",".",".","3"],["4",".",".","8",".","3",".",".","1"],["7",".",".",".","2",".",".",".","6"],[ ".","6",".",".",".",".","2","8","."],[".",".",".","4","1","9",".",".","5"],[".",".",".",".","8",".",".","7","9"]]

Output: true

Explanation: The provided Sudoku board is valid because each row, column, and 3x3 sub-box contains the digits 1-9 without repetition.

Example 2:

Input:

board = [["8","3",".",".","7",".",".",".","."],["6",".",".","1","9","5",".",".","."],[ ".","9","8",".",".",".",".","6","."],["8",".",".",".","6",".",".",".","3"],["4",".",".","8",".","3",".",".","1"],["7",".",".",".","2",".",".",".","6"],[ ".","6",".",".",".",".","2","8","."],[".",".",".","4","1","9",".",".","5"],[".",".",".",".","8",".",".","7","9"]]

Output: false

Explanation: The provided Sudoku board is invalid because the top-left 3x3 sub-box contains two occurrences of the digit '8'.

Constraints:

Time Complexity

O(9^(n*n))

Space Complexity

O(n*n)