Valid Sudoku

最新推荐文章于 2021-03-02 12:20:25 发布

最新推荐文章于 2021-03-02 12:20:25 发布 · 74 阅读

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本文介绍了一种通过Java实现的方法来验证一个数独是否有效。该方法检查每一行、每一列以及每一个九宫格内的数字是否重复，确保数独遵循基本规则。空单元格用字符'.'表示，不参与验证。

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.

public class Solution {
    public boolean isValidSudoku(char[][] board) {
        Set<Character> set = new HashSet<Character>();
        for (int i = 0; i < board.length; i++) {
        	set.clear();
        	for (int j = 0; j < board.length; j++) {
        		if (board[i][j]!='.' && !set.add(board[i][j])) {
        			return false;
        		}
        	}
        }
        for (int i = 0; i < board.length; i++) {
        	set.clear();
        	for (int j = 0; j < board.length; j++) {
        		if (board[j][i]!='.' && !set.add(board[j][i])) {
        			return false;
        		}
        	}
        }
        for (int i = 0; i < board.length/3; i++) {
        	for (int j = 0; j < board.length/3; j++) {
        		set.clear();
        		for (int a = i*3; a < i*3+3; a++) {
        			for (int b = j*3; b < j*3+3; b++) {
        				if (board[a][b]!='.' && !set.add(board[a][b])) {
                			return false;
                		}
        			}
        		}
        	}
        }
        return true;
    }
}