Why we are intializing inc ans exc by 0

Why we are intializing inc ans exc by 0

You mean variables

inc, ans, exc

initially?

You don’t really need to initialize ans, exc.

But, we need to initialize at least inc, because it is possible that the if codition is not executed and therefore the value in inc will be just garbage value, which will cause problem in

ans = max(inc, exc);