// If the sum of all factors of a number is equal to the number, then the number is perfect
// Factors of a number are numbers that divide the number evenly
// 6
// factors = 1, 2, 3
// 1 + 2 + 3 = 6
object PerfectNumberApp {
def isPerfect(n: Int): Boolean = {
if (n < 2) return false
val limit = math.sqrt(n).toInt
val sum = (1 to limit).foldLeft(0) { (acc, i) =>
if (n % i == 0) {
val pair = n / i
if (i == pair) acc + i
else acc + i + pair
} else acc
}
sum - n == n
}
def main(args: Array[String]): Unit = {
println("Perfect numbers up to 10,000:")
(1 to 10000).foreach { num =>
if (isPerfect(num)) println(num)
}
}
}
/*
run:
Perfect numbers up to 10,000:
6
28
496
8128
*/
