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In this post, you will find the solution for the **Valid Sudoku** **in C++, Java & Python-LeetCode problem**. We are providing the **correct and tested solutions** to coding problems present on **LeetCode**. If you are not able to solve any problem, then you can take help from our Blog/website.

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** Link for the Problem** – Valid Sudoku– LeetCode Problem

Valid Sudoku– LeetCode Problem

**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`'.'`

.

Valid Sudoku– LeetCode Solutions

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; } };

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; } }

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