sudoku solver

class Solution {
    public void solveSudoku(char[][] board) {
        Sudoku(board);
    }
    public boolean Sudoku(char[][] board) {
        for(int i=0;i<9;i++){
            for(int j=0;j<9;j++){
                if(board[i][j]=='.'){
                    for(char c='1'; c<='9'; c++){
                        if(isValid(board, i, j, c)){
                            board[i][j]=c;
                            if(Sudoku(board)) return true;
                            else board[i][j]='.';
                        }
                    }
                    return false;
                }
            }
        }
        return true;
    }
    public static boolean isValid(char[][] board, int row, int col, char c) {
    for (int i = 0; i < 9; i++) {
      if (board[i][col] == c)
        return false;

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

      if (board[3 * (row / 3) + i / 3][3 * (col / 3) + i % 3] == c)
        return false;
    }
    return true;
  }

}