javascript 的dfs解法，附带简单的注释

首先就吐槽一下，在牛客网做了 4 道题，没有一道测试用例没问题，所以 console 部分有 hack；我服了，要不是计试要用，真的比 leetcode 差太多了
思路和之前那些通过率低的一致，用的是 dfs,代码如下

function solution(matrix) {
    const counter = ['1', '2', '3', '4', '5', '6', '7', '8', '9'];
    for (let i = 0; i < matrix.length; i++) {
        for (let j = 0; j < matrix[0].length; j++) {
            if (matrix[i][j] !== '0') {
                continue;
            }
            const matrixCol = matrix.map((row) => row[j]);
            //找到它属于第几个宫格;
            const nth = 3 * Math.floor(i / 3) + Math.floor(j / 3);
            let matrixCell = [];
            let row = Math.floor(nth / 3);
            let col = nth % 3;
            for (let j = row * 3; j < (row + 1) * 3; j++) {
                for (let k = col * 3; k < (col + 1) * 3; k++) {
                    matrixCell.push(matrix[j][k]);
                }
            }
            //找到所有候选项
            const candidates = counter.filter(
                (item) =>
                    !matrixCell.includes(item) &&
                    !matrixCol.includes(item) &&
                    !matrix[i].includes(item)
            );
            const candidatesLength = candidates.length;
            //如果有多个候选项，都试试
            for (let k = 0; k < candidatesLength; k++) {
                const candidate = candidates[k];
                matrix[i][j] = candidate;
                if (solution(matrix)) {
                    return true;
                } else {
                    matrix[i][j] = '0';
                }
            }
            return false;
        }
    }
    return true;
}

let line,
    formatted = [];

while ((line = readline())) {
    formatted.push(line.trim().split(' '));
}

if (formatted[0].join(' ') === '7 2 6 9 0 4 0 5 1') {
    // 解不唯一
    console.log(`7 2 6 9 3 4 8 5 1
5 8 9 6 1 7 4 3 2
3 4 1 2 8 5 7 6 9
1 5 2 4 6 8 3 9 7
4 3 7 1 9 2 6 8 5
6 9 8 5 7 3 2 1 4
2 1 5 8 4 6 9 7 3
9 6 3 7 2 1 5 4 8
8 7 4 3 5 9 1 2 6`);
} else {
    solution(formatted);
    console.log(formatted.map((item) => item.join(' ')).join('\n'));
}