javascript - 数字根排序算法

Question

我正在通过 codefight 的挑战，所有测试都通过了，除了 1 个“隐藏测试”，我无法看到插入的测试数据...我正在寻求帮助，指出我在做什么我的解决方案缺少或失败的测试用例。

问题:

Digit root of some positive integer is defined as the sum of all of its digits.

You are given an array of integers. Sort it in such a way that if a comes before b then the digit root of a is less than or equal to the digit root of b. If two numbers have the same digit root, the smaller one (in the regular sense) should come first. For example 4 and 13 have the same digit root, however 4 < 13 thus 4 comes before 13 in any digitRoot sorting where both are present.

Example

For a = [13, 20, 7, 4], the output should be [20, 4, 13, 7].

[time limit] 4000ms (js) [input] array.integer a

Array of positive integers.

[output] array.integer

我的解决方案:

function digitRootSort(a) {
    "use strict";

    function getDigitalRoot(n) {
        let _dr = n
            .toString()
            .split('')
            .reduce((acc, val, i) => {
                return acc += parseInt(val)
            }, 0)
            .toString()

        if (_dr.length > 1) {
            return getDigitalRoot(_dr)
        }

        return parseInt(_dr)
    }

    const digitalRootSorted = a.sort((a,b) => {
        const _a = getDigitalRoot(a)  
        const _b = getDigitalRoot(b)

        return _a < _b 
            ? -1 
            :  _a > _b
                ? 1
                : a < b 
                    ? -1
                    : a === b
                        ? 0
                        : 1
    })

    return digitalRootSorted
}

Answer 1

您可以对数字求和并使用链式方法，例如

const sum = n => [...n.toString()].reduce((a, b) => +a + +b),
      array = [13, 20, 7, 4];

array.sort((a, b) => sum(a) - sum(b) || a - b);

console.log(array);