Leetcode 36 Valid Sudoku Solution in java | 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

public boolean isValidSudoku(char[][] board) {

boolean[][] rows = new boolean[9][9];

boolean[][] columns = new boolean[9][9];

boolean[][] squares = new boolean[9][9];

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

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

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

continue;

}

int num = board[i][j] - '1';

if (rows[i][num]) {

return false;

}

rows[i][num] = true;

if (columns[j][num]) {

return false;

}

columns[j][num] = true;

if (squares[(i / 3) * 3 + j / 3][num]) {

return false;

}

squares[(i / 3) * 3 + j / 3][num] = true;

}

}

return true;

}