Home / Questions / 116980
Accepted
Norak
Asked: 2020-11-14 03:31:44 +0800 CST 2020-11-14 03:31:44 +0800 CST

Possible combinations/pairs in the same array

  • 772

I want to match all the elements of the same array with each other, but an element cannot be matched with itself.

The code I got is the following:

        function combine(list) {

        var pairs = new Array((list.length * (list.length - 1)) / 2),

        pos = 0;

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

            for (var j = i + 1; j < list.length; j++) {

                pairs[pos++] = [list[i], list[j]];

            }

        }

        return pairs;

        }

    var result = combine([1, 2, 3, 4]);
    console.log("Combinaciones = "+ JSON.stringify(result));

The result I expect as a solution will be:

Combinaciones = [[1,2],[1,3],[1,4],[2,1],[2,3],[2,4],[3,1],[3,2],[3,4],[4,1],[4,2],[4,3]]

However I get this and I don't know where the error is:

Combinaciones = [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]];

So for example if it checks 1.2 I also want it to check 2.1 but not each number with itself.

How to obtain the combinations of possible pairs in both senses, only omitting the one of a number with itself?

javascript

1 Answers

  1. Best Answer

    The variable j in the second loop would have to be initialized to 0 , otherwise it would take the value two when the first loop was in the first iteration. It would look like this:

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

        for (var j = 0; j < list.length; j++) {

            pairs[pos++] = [list[i], list[j]];

        }

    }
    • 3