javascript - 查找结果为其他3个数组元素之和的数组元素，d = a + b + c(Find array element which results as a sum of other 3 array elements, d = a + b + c)

Question

Task You are given a sorted integer array arr.

(任务您将获得一个排序的整数数组arr。)

It contains several unique integers(negative, positive, or zero).

(它包含几个唯一的整数（负数，正数或零）。)

Your task is to find the largest d such that a + b + c = d, where a, b, c, and d are distinct elements of arr.

(您的任务是找到最大的d，以使a + b + c = d，其中a，b，c和d是arr的不同元素。)

If no such an element d found, return null.

(如果找不到这样的元素d，则返回null。)

Example:

(例：)

For arr = [2,3,5,7,12], the output should be 12 (this array passes my function correctly)

(对于arr = [2,3,5,7,12]，输出应为12（此数组正确传递了我的函数）)

For arr = [-100,-1,0,7,101], the output should be 0 (this one does not pass)

(对于arr = [-100，-1,0,7,101]，输出应为0（此不通过）)

I could manage the positive numbers check but my function miserably fails with negatives

(我可以管理正数检查，但是我的功能由于负数而失败)

function findD(arr) {

    myArr = arr.sort((a, b) => b - a);

    for (var i = 0; i < myArr.length; i++) {

        for (var k = i + 1; k < myArr.length - 2; k++) {

            var j = k + 1,
                d = myArr.length - 1;

            while (j < d) {

                let sum = myArr[k] + myArr[j] + myArr[d];

                if (sum == myArr[i]) {
                    return myArr[i];
                } else if (sum < myArr[i]) {
                    d--;
                } else if (sum > myArr[i]) {
                    j++;
                }
            }
        }
    }
    return null
}

how to handle negative values in the array?

(如何处理数组中的负值？)

  ask by metamorph_online translate from so

Answer 1

This is a known logic problem, there are plenty of efficient algorithms here: https://www.geeksforgeeks.org/find-largest-d-in-array-such-that-abcd/

(这是一个已知的逻辑问题，这里有很多有效的算法： https : //www.geeksforgeeks.org/find-largest-d-in-array-such-that-abcd/)

You will just need to write it in javascript (you can get the logic from java/c++/python)

(您只需要用javascript编写即可（您可以从java / c ++ / python获取逻辑）)