lc-36

//Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be v
//alidated 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 with
//out repetition. 
// 
//
// Note: 
//
// 
// A Sudoku board (partially filled) could be valid but is not necessarily solva
//ble. 
// 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
// 
//
// Example 2: 
//
// 
//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 inval
//id.
// 
//
// 
// Constraints: 
//
// 
// board.length == 9 
// board[i].length == 9 
// board[i][j] is a digit 1-9 or '.'. 
// 
// Related Topics Array Hash Table Matrix 
// 👍 5534 👎 753


//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
    public boolean isValidSudoku(char[][] board) {
        for (int i = 0; i < 9; i++) {
            if (!isValid(board, i, 0) || !isValid(board, i, 1) || !isValid(board, i, 2)) {
                return false;
            }
        }

        return true;
    }

    private boolean isValid(char[][] board, int index, int mode) {
        boolean[] isOccupied = new boolean[9];

        for (int i = 0; i < 9; i++) {
            char ch = 0;

            if (mode == 0) {
                ch = board[index][i];
            } else if (mode == 1) {
                ch = board[i][index];
            } else {
                ch = board[index/3*3 + i / 3][index % 3 * 3 + i % 3];
            }

            if (ch == '.') {
                continue;
            } else {
                int chIn = ch - '1';

                if (chIn < 0 || chIn > 8) {
                    return false;
                } else if (isOccupied[chIn]) {
                    return false;
                } else {
                    isOccupied[chIn] = true;
                }
            }
        }

        return true;
    }
}
//leetcode submit region end(Prohibit modification and deletion)