Doubt related to modulus of -ve values

#1

Here in the code, we are not checking that whether the sum is -ve or +ve.

Still we are doing sum%=n for both +ve and -ve values of sum. Then why there is a need to do the sum = (sum+n)%n operation?

And what will -12%5 will give?

#2

Why don’t we test it out with an example?

Take −100 mod 8=4. This is because 8⋅−13=−104. The remainder is 4.

So now let’s take (37−54) mod 5. It’s equal to −17 mod 5=3. Substitute in and do the computation: Method 1 gives 3, which is what we want, and method 2 gives −2, so the correct approach is method 1.

#3

Just confirm me, what is method 1 and 2?

#4

method 1 is (a+n)%n to take modulo

#5

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