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In this post, you will find the solution for the **Sudoku Solver** **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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Leetcode has a huge number of test cases and questions from interviews too like Google, Amazon, Microsoft, Facebook, Adobe, Oracle, Linkedin, Goldman Sachs, etc. LeetCode helps you in getting a job in Top MNCs. To crack FAANG Companies, LeetCode problems can help you in building your logic.

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

Sudoku Solver– LeetCode Problem

**Problem:**

Write a program to solve a Sudoku puzzle by filling the empty cells.

A sudoku solution must satisfy **all of the following rules**:

- Each of the digits
`1-9`

must occur exactly once in each row. - Each of the digits
`1-9`

must occur exactly once in each column. - Each of the digits
`1-9`

must occur exactly once in each of the 9`3x3`

sub-boxes of the grid.

The `'.'`

character indicates empty cells.

**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:[["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"]]Explanation:The input board is shown above and the only valid solution is shown below:

**Constraints:**

`board.length == 9`

`board[i].length == 9`

`board[i][j]`

is a digit or`'.'`

.- It is
**guaranteed**that the input board has only one solution.

Sudoku Solver– LeetCode Solutions

class Solution { public: void solveSudoku(vector<vector<char>>& board) { solve(board, 0); } private: bool solve(vector<vector<char>>& board, int s) { if (s == 81) return true; const int i = s / 9; const int j = s % 9; if (board[i][j] != '.') return solve(board, s + 1); for (char c = '1'; c <= '9'; ++c) if (isValid(board, i, j, c)) { board[i][j] = c; if (solve(board, s + 1)) return true; board[i][j] = '.'; } return false; } bool isValid(vector<vector<char>>& board, int row, int col, char c) { for (int i = 0; i < 9; ++i) if (board[i][col] == c || board[row][i] == c || board[3 * (row / 3) + i / 3][3 * (col / 3) + i % 3] == c) return false; return true; } };

class Solution { public void solveSudoku(char[][] board) { dfs(board, 0); } private boolean dfs(char[][] board, int s) { if (s == 81) return true; final int i = s / 9; final int j = s % 9; if (board[i][j] != '.') return dfs(board, s + 1); for (char c = '1'; c <= '9'; ++c) if (isValid(board, i, j, c)) { board[i][j] = c; if (dfs(board, s + 1)) return true; board[i][j] = '.'; } return false; } private boolean isValid(char[][] board, int row, int col, char c) { for (int i = 0; i < 9; ++i) if (board[i][col] == c || board[row][i] == c || board[3 * (row / 3) + i / 3][3 * (col / 3) + i % 3] == c) return false; return true; } }

class Solution: def solveSudoku(self, board: List[List[str]]) -> None: def isValid(row: int, col: int, c: chr) -> bool: for i in range(9): if board[i][col] == c or \ board[row][i] == c or \ board[3 * (row // 3) + i // 3][3 * (col // 3) + i % 3] == c: return False return True def solve(s: int) -> bool: if s == 81: return True i = s // 9 j = s % 9 if board[i][j] != '.': return solve(s + 1) for c in string.digits[1:]: if isValid(i, j, c): board[i][j] = c if solve(s + 1): return True board[i][j] = '.' return False solve(0)

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