CodingMediumcod-g124

Subject SudokuLevel Mid–Senior~22 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a 9x9 Sudoku board where '.' marks an empty cell, determine whether the currently filled cells are valid: no row, column, or 3x3 box contains a repeated digit '1'-'9'. You only validate the partial state; you do not solve it. Return True if valid, else False.

Implement

is_valid_sudoku(board: list[list[str]]) → bool

Examples

[[["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"]]]

outtrue

What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

Learn the concepts

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.