/*
roundUp(n, multiple)
--------------------
Rounds the integer n *up* to the nearest multiple of `multiple`.
Mathematically:
result = ceil(n / multiple) * multiple
We use integer arithmetic for efficiency:
(n + multiple - 1) / multiple → smallest integer ≥ n/m
*/
fn round_up(n: i32, multiple: i32) -> i32 {
if multiple <= 0 {
// Defensive programming: avoid undefined behavior.
// In real-world code, you'd throw or handle this differently.
return n;
}
// Efficient integer rounding up:
((n + multiple - 1) / multiple) * multiple
}
fn main() {
println!("roundUp(53, 20) = {}", round_up(53, 20));
println!("roundUp(68, 30) = {}", round_up(68, 30));
println!("roundUp(7, 100) = {}", round_up(7, 100));
println!("roundUp(119, 100) = {}", round_up(119, 100));
println!("roundUp(781, 100) = {}", round_up(781, 100));
println!("roundUp(1026, 100) = {}", round_up(1026, 100));
println!("roundUp(11689, 1000) = {}", round_up(11689, 1000));
}
/*
run:
roundUp(53, 20) = 60
roundUp(68, 30) = 90
roundUp(7, 100) = 100
roundUp(119, 100) = 200
roundUp(781, 100) = 800
roundUp(1026, 100) = 1100
roundUp(11689, 1000) = 12000
*/
