My Iterative Algo fails

#1

I used algo in which the ans returns whenever the desired difference occurs but giving wrong ans.

Here is my code

#2

It gives wrong answer for this test case
2
25 25251

This is because there is no way other than comparing a+b and b+a to check.
When the first 2 digits are compared you are left with deciding to choose from 251 and 25, and you choose 251, instead you need to loop again for the length of b, until you compare 1 from 251 and 2 from 25. So you need to compare a+b and b+a.

#3

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