Distinguishing extra element from two arrays?

Question

One of my friend was asked this question in an interview -

• You have given two integer arrays each of size 10.
• Both contains 9 equal elements (say 1 t

Answer 1

How about getting the total sum for each of the arrays and subtracting one from the other? The difference is the extra element.

eg: A = 1,2,3,4,5 B = 1,2,3,4

sum(A) = 15, sum(B) = 10; 15 - 10 = 5 which is the extra element.