function pairwise(arr, arg) {
const indices =[]
arr.forEach((e,i) => {
let res = arr.filter((e1,i1)=> e1==(arg-e) && i1>i)[0];
let ind = arr.indexOf(res,i+1)
if (ind!=-1) {
arr[i]='x'
arr[ind]='x'
indices.push(i,ind)
};
});
return indices.reduce((a,b)=> a+b, 0)
}
Thank you, for your contribution. For future contributions, please wrap your solution within :
[details]
```
code goes here...
```
[/details]
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