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有效的数独

请你判断一个 9 x 9 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。

数字 1-9 在每一行只能出现一次。 数字 1-9 在每一列只能出现一次。 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)

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。
  • 空白格用 '.' 表示。

示例 1:

有效的数独

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(1-9)或者 '.'

思路

分别记录行, 列, 宫格 的数值, 一旦发现任何重复的数值则为 false 否则为 true

一次遍历,记录行/列/宫格

TypeScript
function isValidSudoku(board: string[][]): boolean {
    let arr = [];
    for (let i = 0; i < board.length; i++) {
        const row = board[i];
        for (let j = 0; j < row.length; j++) {
            const col = row[j];
            // 初始化保存的数组
            if (!arr[j]) arr[j] = {row: [], col: [], chunk: []};
            // 不记录空白
            if (col === '.') continue;
            // 判断行是否重复
            if (arr[i].row.includes(col)) return false;
            // 判断列是否重复
            if (arr[j].col.includes(col)) return false;
            // 判断块是否重复
            let index:number;
            // TODO: 下面这一段应该可以优化
            if (i<3&&j<3)index = 0;
            else if (i<6&&j<3)index = 1;
            else if (i<9&&j<3)index = 2;
            else if (i<3&&j<6)index = 3;
            else if (i<6&&j<6)index = 4;
            else if (i<9&&j<6)index = 5;
            else if (i<3&&j<9)index = 6;
            else if (i<6&&j<9)index = 7;
            else if (i<9&&j<9)index = 8;
            if (arr[index].chunk.includes(col)) return false;
            // 记录行
            arr[i].row.push(col);
            // 记录列
            arr[j].col.push(col);
            // 记录块
            arr[index].chunk.push(col);
        }
    }
    return true;
};

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