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【leetcode-数组】有效的数独
阅读量:552 次
发布时间:2019-03-09

本文共 1901 字,大约阅读时间需要 6 分钟。

判断一个 9x9 的数独是否有效。只需要根据以下规则,验证已经填入的数字是否有效即可。

  1. 数字 1-9 在每一行只能出现一次。
  2. 数字 1-9 在每一列只能出现一次。
  3. 数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。

上图是一个部分填充的有效的数独。

数独部分空格内已填入了数字,空白格用 '.' 表示。

示例 1:

输入:[  ["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"]]输出: true

示例 2:

输入:[  ["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"]]输出: false解释: 除了第一行的第一个数字从 5 改为 8 以外,空格内其他数字均与 示例1 相同。     但由于位于左上角的 3x3 宫内有两个 8 存在, 因此这个数独是无效的。

说明:

  • 一个有效的数独(部分已被填充)不一定是可解的。
  • 只需要根据以上规则,验证已经填入的数字是否有效即可。
  • 给定数独序列只包含数字 1-9 和字符 '.' 。
  • 给定数独永远是 9x9 形式的。

思路:用三个二维数组rawFlagcolFlag以及cellFlag,分别记录行位置的数据是否重复;列位置的数据是否有重复;3*3宫内是否有重复;

class Solution {    public boolean isValidSudoku(char[][] board) {        boolean[][] rowFlag = new boolean[9][9];        boolean[][] colFlag = new boolean[9][9];        boolean[][] cellFlag = new boolean[9][9];                int m = board.length;        int n = board[0].length;        for(int i=0;i
='1'&&cc<='9') { int c = cc-'1'; if(rowFlag[i][c] || colFlag[j][c] || cellFlag[3*(i/3)+j/3][c]) { return false; } rowFlag[i][c]=true; colFlag[j][c] =true; cellFlag[3*(i/3)+j/3][c]=true; } } } return true; }}

 

转载地址:http://ivhiz.baihongyu.com/

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