Solve Sudoku (Backtracking)?

bool SolveSudoku(char[][] board)

for (int i = 0; i < 9; i++)

for (int j = 0; j < 9; j++)

Follow on:

if (board[i][j] == '.')

for (char c = '1'; c <= '9'; c++)

if (IsValid(board, i, j, c))

board[i][j] = c;

if (SolveSudoku(board))

return true;

else

board[i][j] = '.';

return false;

return true;

bool IsValid(char[][] board, int row, int col, char c)

for (int i = 0; i < 9; i++)

if (board[row][i] == c) return false;

if (board[i][col] == c) return false;

if (board[3 * (row / 3) + i / 3][3 * (col / 3) + i % 3] ==

c) return false;

return true;

Explanation:

Backtracking tries digits 1-9 in empty cells, validating constraints.