Code Room
CodingHard
Question
Solve a 9x9 Sudoku. The board is given as a list of 9 lists of integers, where 0 marks an empty cell and 1-9 are filled. Fill the empty cells so each row, column, and 3x3 box contains the digits 1-9 exactly once, and return the completed board. Each puzzle has exactly one solution.
Implement
solve_sudoku(board: list[list[int]]) → list[list[int]]Examples
in
[[[5,3,0,0,7,0,0,0,0],[6,0,0,1,9,5,0,0,0],[0,9,8,0,0,0,0,6,0],[8,0,0,0,6,0,0,0,3],[4,0,0,8,0,3,0,0,1],[7,0,0,0,2,0,0,0,6],[0,6,0,0,0,0,2,8,0],[0,0,0,4,1,9,0,0,5],[0,0,0,0,8,0,0,7,9]]]out[[5,3,4,6,7,8,9,1,2],[6,7,2,1,9,5,3,4,8],[1,9,8,3,4,2,5,6,7],[8,5,9,7,6,1,4,2,3],[4,2,6,8,5,3,7,9,1],[7,1,3,9,2,4,8,5,6],[9,6,1,5,3,7,2,8,4],[2,8,7,4,1,9,6,3,5],[3,4,5,2,8,6,1,7,9]]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.