/*
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
*/
function roundUp(int $n, int $multiple): int {
if ($multiple <= 0) {
// Defensive programming: avoid undefined behavior.
// In real-world code, you'd throw or handle this differently.
return $n;
}
// Efficient integer rounding up:
return intdiv($n + $multiple - 1, $multiple) * $multiple;
}
// main()
echo "roundUp(53, 20) = " . roundUp(53, 20) . "\n";
echo "roundUp(68, 30) = " . roundUp(68, 30) . "\n";
echo "roundUp(7, 100) = " . roundUp(7, 100) . "\n";
echo "roundUp(119, 100) = " . roundUp(119, 100) . "\n";
echo "roundUp(781, 100) = " . roundUp(781, 100) . "\n";
echo "roundUp(1026, 100) = " . roundUp(1026, 100) . "\n";
echo "roundUp(11689, 1000) = " . roundUp(11689, 1000) . "\n";
/*
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
*/
