「前端刷题」36. 有效的数独

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题目

请你判断一个 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。（请参考示例图）

数独部分空格内已填入了数字，空白格用 '.' 表示。

注意：

• 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。

 

示例 1：

输入： 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"]] **输出：**true

示例 2：

输入： 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"]] **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。

 

提示：

• board.length == 9
• board[i].length == 9
• board[i][j] 是一位数字或者 '.'

解题思路

利用map进行查重，
key:"i"i && "j"j && "Math.floor(i / 3),Math.floor(j / 3)"

代码

/**
 * @param {character[][]} board
 * @return {boolean}
 */
var isValidSudoku = function(board) {

let map = new Map();

for(let i=0;i<board.length;i++){
    for(let j=0;j<board[i].length;j++){
        const l = Math.floor(i / 3),
              r = Math.floor(j / 3);
        if(!map.has(`i${i}`))
        map.set(`i${i}`,[]);
        if(!map.has(`j${j}`))
        map.set(`j${j}`,[])
        if(!map.has(`${l}${r}`))
        map.set(`${l}${r}`,[]);
   if(!isNaN(Number(board[i][j]))){
       const num = Number(board[i][j]);
       if(map.get(`${l}${r}`).indexOf(board[i][j]) < 0)
       map.set(`${l}${r}`,[...map.get(`${l}${r}`),board[i][j]]);
       else return false;
    if(map.get(`i${i}`).indexOf(board[i][j]) < 0)
    map.set(`i${i}`,[...map.get(`i${i}`),board[i][j]]);
    else return false;
     if(map.get(`j${j}`).indexOf(board[i][j]) < 0)
    map.set(`j${j}`,[...map.get(`j${j}`),board[i][j]]);
    else return false;
   }
    }
}
return true;

};

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