Another way to get all combination of integers of an array Javascript

Question

I want to iterate an array and find all pairs where their difference is 2

This is what i have so far:

var numberOfCases = 5;
var diff = 2;

var input = [1,5,3,4,2];

getPossiblepairs(input);

function getPossiblepairs(input){
    for(cmp in input){
        for(number in input){
            if((input[cmp] - input[number]) == diff){
                console.log("("+input[cmp]+","+input[number]+")");
            }
        }

    }
}

This works but i still feel guilty using two for loops as the bigO is O(n^2) Is this the only way to do this?

Answer 1

You can do this in O(n log n). Sort the array then go through it in a single pass. Find the difference between the current element and each of the next two, printing out the pair if one is different by 2.