cpp-flashcards/org/study_deck_02/dsa/arrays-hashing/0036-valid-sudoku.org

#+ANKI_DECK: study_deck_02
* TODO 0036. Valid Sudoku :medium:
:PROPERTIES:
:NEETCODE: [[file:../../roadmap.org::*0036. Valid Sudoku][0036. Valid Sudoku]]
:END:

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:*


#+begin_src
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
#+end_src


*Example 2:*


#+begin_src
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: false
Explanation: Same as Example 1, except with the 5 in the top left corner being modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.
#+end_src


*Constraints:*

 - ~board.length == 9~

 - ~board[i].length == 9~

 - ~board[i][j]~ is a digit ~1-9~ or ~'.'~.

** TODO Approach
Write your approach here.

** TODO Python
#+begin_src python
class Solution:
    def isValidSudoku(self, board: List[List[str]]) -> bool:
#+end_src

** TODO C++
#+begin_src cpp
class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        
    }
};
#+end_src