Leetcode 36 Valid Sudoku Solution in c++ | Hindi Coding Community

 

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

class Solution

{

public:

bool isValidSudoku(vector<vector<char> > &board)

{

int used1[9][9] = {0}, used2[9][9] = {0}, used3[9][9] = {0};

for(int i = 0; i < board.size(); ++ i)

for(int j = 0; j < board[i].size(); ++ j)

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

{

int num = board[i][j] - '0' - 1, k = i / 3 * 3 + j / 3;

if(used1[i][num] || used2[j][num] || used3[k][num])

return false;

used1[i][num] = used2[j][num] = used3[k][num] = 1;

}

return true;

}

};