In this post, we are going to solve the** Valid Sudoku** **Leetcode Solution** problem of **Leetcode**. This Leetcode problem is done in many programming languages like C++, Java, and Python.

**Problem**

Determine if a `9 x 9`

Sudoku board is valid. Only the filled cells need to be validated **according to the following rules**:

- Each row must contain the digits
`1-9`

without repetition. - Each column must contain the digits
`1-9`

without repetition. - Each of the nine
`3 x 3`

sub–boxes of the grid must contain the digits`1-9`

without repetition.

**Note:**

- A Sudoku board (partially filled) could be valid but is not necessarily solvable.
- Only the filled cells need to be validated according to the mentioned rules.

**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

**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:falseExplanation:Same as Example 1, except with the5in the top left corner being modified to8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.

**Constraints:**

`board.length == 9`

`board[i].length == 9`

`board[i][j]`

is a digit`1-9`

or`'.'`

.

Now, let’s see the leetcode solution of **Valid Sudoku****Leetcode Solution**.

**Valid Sudoku Leetcode Solution in Python**

class Solution: def isValidSudoku(self, board: List[List[str]]) -> bool: seen = set() for i in range(9): for j in range(9): c = board[i][j] if c == '.': continue if c + '@row ' + str(i) in seen or \ c + '@col ' + str(j) in seen or \ c + '@box ' + str(i // 3) + str(j // 3) in seen: return False seen.add(c + '@row ' + str(i)) seen.add(c + '@col ' + str(j)) seen.add(c + '@box ' + str(i // 3) + str(j // 3)) return True

**Valid Sudoku** **Leetcode Solution** **in CPP**

class Solution { public: bool isValidSudoku(vector<vector<char>>& board) { unordered_set<string> seen; for (int i = 0; i < 9; ++i) for (int j = 0; j < 9; ++j) { if (board[i][j] == '.') continue; const string c(1, board[i][j]); if (!seen.insert(c + "@row" + to_string(i)).second || !seen.insert(c + "@col" + to_string(j)).second || !seen.insert(c + "@box" + to_string(i / 3) + to_string(j / 3)) .second) return false; } return true; } };

**Valid Sudoku Leetcode Solution in Java**

class Solution { public boolean isValidSudoku(char[][] board) { Set<String> seen = new HashSet<>(); for (int i = 0; i < 9; ++i) for (int j = 0; j < 9; ++j) { if (board[i][j] == '.') continue; final char c = board[i][j]; if (!seen.add(c + "@row" + i) || !seen.add(c + "@col" + j) || !seen.add(c + "@box" + i / 3 + j / 3)) return false; } return true; } }

**Note:** This problem ** Valid Sudoku** is generated by

**Leetcode**but the solution is provided by

**Chase2learn**This tutorial is only for Educational and Learning purposes.