Can someone help with this?
why do greedy techniques work here?
The question link
Why not for you ?, Basically, after sorting both arrays, if we pick any two indices i and j , then min(a[i],b[i]) + min(a[j],b[j]) is greater than or equal to min(a[i],b[j]) + min(a[j],b[i]) .
You can try to convince yourself for the above inequality.