Find the sum of all the minimum differences of pairs in array

Question

I want to find the differences between all closest-neigbour pairs and sum them, given the input array is even-length.

I have this code right now but it only gives the minimum difference of one pair. How do I go about to achieve this? So take out the pairs who have already been summed and calculate with the rest of the pairs.

 var lowestDiff = Infinity;
arr.sort((a, b) => a - b);
for (var i = 0; i < arr.length - 1; i++) {
    lowestDiff = Math.min(lowestDiff, Math.abs(arr[i] - arr[i + 1]));
}
   console.log(lowestDiff);

So for example if the input is: [6,2,3,6], output would be: 1 because 6 pairs with 6 and 2 pairs with 3

So essentially i want to pair an element with another element which is closest to them, and get that difference. And sum them.

Please provide some more examples as the question is not clear. — saurabh sisodia, Jul 28 '20 at 22:47
@Sven.hig no 1 because 2 pairs up with his closest neighbour - 3. — Y_Lakdime, Jul 28 '20 at 22:51
Considering, you say *'...all possible pairs...'* shouldn't your example result into 13 (6-2 + 2-3 + 6-3 + 6-3 + 6-2 + 6-6) ? — Yevhen Horbunkov, Jul 28 '20 at 22:52
@YevgenGorbunkov no because an element can only be in one pair - his closest neighbour — Y_Lakdime, Jul 28 '20 at 22:53
Then it seems to contradict *'all possible'*-condition. So it is closest (in terms of position in sorted copy) only? — Yevhen Horbunkov, Jul 28 '20 at 22:56
@saurabhsisodia yes, so compare an element with the others and take the one with the least difference — Y_Lakdime, Jul 28 '20 at 22:58
So for `[1,4,5,9]` the expected result would be 7 (4-1 + 9-5)? Even though the pair 4/5 is much closer? — Bergi, Jul 28 '20 at 23:25

saurabh sisodia · Accepted Answer · 2020-07-31T16:44:57.610

1

As you need to find the sum of the minimum difference pairs from an even length array. One thing to note: here is that-: After sorting the given array closest pairs will be adjacent to each other So, I think below code should work

function min_difference(arr)
{
       arr.sort(function(a, b) {
          return a - b;
                });
       let ans=0;
       for (let i=1;i<arr.length;i+=2)
      {
          ans+=(arr[i]-arr[i-1]);
      }
       return ans;
}
var arr=[2,2,2,2];
console.log(min_difference(arr));

edited Jul 31 '20 at 16:44

answered Jul 28 '20 at 23:11

saurabh sisodia

312
1
8

The explanation is good, but [the sorting does not work](https://stackoverflow.com/q/1063007/1048572) and I'd recommend a `for` loop instead of a `while` loop. – Bergi Jul 28 '20 at 23:28
1

@Bergi Thank You very much. I have updated my answer. – saurabh sisodia Jul 28 '20 at 23:47
@saurabhsisodia : `Math.abs()` in above case seems to do only to things: slow down your code and make it more verbose. As long as your items are sorted in ascending order, the difference between them will be positive (or 0) anyways. Also, I would recommend to wrap that code block into function which would return `ans` rather than `console.log()` it. You may consider to turn your code into live-snippet, as well. – Yevhen Horbunkov Jul 31 '20 at 07:43
@saurabhsisodia : you're supposed to do rather something, like `function min_difference(arr){..`, aren't you? – Yevhen Horbunkov Jul 31 '20 at 16:11

Find the sum of all the minimum differences of pairs in array

1 Answers1