Valid Sudoku 25 XP Medium

LeetCode Ctrl+Enter Run Ctrl+S Save

Determine if a 9×9 Sudoku board is valid. Only the filled cells need to be validated according to these rules:

Each row must contain digits 1-9 without repetition
Each column must contain digits 1-9 without repetition
Each of the nine 3×3 sub-boxes must contain digits 1-9 without repetition

Use three sets of hash sets — one for rows, columns, and boxes. For each filled cell, check all three sets.

The 3×3 box index can be computed as (row // 3, col // 3).

📋 Instructions

For simplicity, validate this smaller example: Check if the row `[5, 3, '.', '.', 7, '.', '.', '.', '.']` has no duplicate digits. Print `True` if there are no duplicate digits (ignoring '.'), `False` otherwise. Then check `[5, 3, '.', '.', 5, '.', '.', '.', '.']` — this has duplicate 5s. Print both results.

For each row, create a set. Iterate through each element, skip '.', and check if the number is already in the set. If yes, it's invalid.

🧪 Test Cases

Input

is_valid_row([5, 3, '.', '.', 7, '.', '.', '.', '.'])

Expected

True

Boolean check

Input

is_valid_row([5, 3, '.', '.', 5, '.', '.', '.', '.'])

Expected

False

Boolean check

← Previous Next Exercise →

main.py

Hi! I'm Rex 👋

Output

Ready. Press ▶ Run or Ctrl+Enter.

›