Single-byte checksum of a payload
Many lightweight protocols use a one-byte checksum: just the sum of all bytes modulo 256.
- Each element in the payload is a byte value (0–255).
- The checksum is the sum of all bytes modulo 256.
- An empty payload has a checksum of 0.
checksumByte(payload: list<int>) → int
Java needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
int checksumByte(List<Integer> payload) {
}Worked examples
| Call | Result |
|---|---|
checksumByte(Main.<Integer>ls(1, 2, 3)) | 6 |
checksumByte(Main.<Integer>ls(255, 1)) | 0 |
checksumByte(Main.<Integer>ls()) | 0 |
checksumByte(Main.<Integer>ls(128, 128)) | 0 |
Hint
Add every element, then take the remainder when divided by 256.
Reference solution in Java
int checksumByte(List<Integer> payload) {
int sum = 0;
for (int b : payload) sum += b;
return sum % 256;
}