CodingHardcod-g802

Subject SudokuLevel Senior–Staff~35 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

You are given a 4x4 Sudoku board as a list of 4 rows; each cell holds 0 (blank) or a value in 1..4. A completion fills every blank so that each row, each column, and each of the four 2x2 boxes contains the digits 1,2,3,4 exactly once. The given clues are guaranteed not to already violate these rules. Return the number of valid completions (0 if none).

Implement

count_sudoku_completions(board: list[list[int]]) → int

Examples

in[[[1,2,3,4],[3,4,1,2],[2,1,4,3],[4,3,2,0]]]out1

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.