36. Valid Sudoku

Problem

Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.

The Sudoku board could be partially filled, where empty cells are filled with the character '.'.

A partially filled sudoku which is valid.

Note: A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.

Related Topics:

Hash Table

Analysis

利用 HashSet 的特性，判断 行、列、块 有无重复数字。

Code

class Solution {

    fun isValidSudoku(board: Array<CharArray>): Boolean {

        val valid = HashSet<String>()

        for (i in 0..8) {
            for (j in 0..8) {
                if (board[i][j] != '.' && (
                                !valid.add(board[i][j] + " in block " + i / 3 + " - " + j / 3) ||
                                        !valid.add(board[i][j] + " in row " + i) ||
                                        !valid.add(board[i][j] + " in column " + j))) {

                    return false
                }
            }
        }

        return true
    }
}