Maximize Sum after 1 Flip

Elliot has two buckets, Bucket $A$ and Bucket $B$. Each bucket has $N$ balls in it and each ball has a number written on it. You are given two arrays $A =[A_1,A_2,\dots,A_N]$ and $B=[B_1,B_2,\dots,B_N]$, each of length $N$, where $A_i$ and $B_i$ represent the numbers written on the $i^{th}$ ball in Bucket $A$ and Bucket $B$ respectively. Angela has allowed Elliot to swap the balls in the two buck