51 lines
1.5 KiB
Java
51 lines
1.5 KiB
Java
|
// Author: Rodney Shaghoulian
|
||
|
|
// Github: github.com/rshaghoulian
|
||
|
|
// HackerRank: hackerrank.com/rshaghoulian
|
||
|
|
|
||
|
|
import java.util.*;
|
||
|
|
|
||
|
|
interface AdvancedArithmetic {
|
||
|
|
int divisor_sum(int n);
|
||
|
|
}
|
||
|
|
|
||
|
|
class MyCalculator implements AdvancedArithmetic {
|
||
|
|
// Runtime: O(n^(1/2))
|
||
|
|
// Space Complexity: O(1)
|
||
|
|
public int divisor_sum(int n) {
|
||
|
|
int sum = 0;
|
||
|
|
int sqrt = (int) Math.sqrt(n);
|
||
|
|
for (int i = 1; i <= sqrt; i++) {
|
||
|
|
if (n % i == 0) { // if "i" is a divisor
|
||
|
|
sum += i + n/i; // add both divisors
|
||
|
|
}
|
||
|
|
}
|
||
|
|
/* If sqrt is a divisor, we should only count it once */
|
||
|
|
if (sqrt * sqrt == n) {
|
||
|
|
sum -= sqrt;
|
||
|
|
}
|
||
|
|
return sum;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
class Solution {
|
||
|
|
public static void main(String []args) {
|
||
|
|
MyCalculator my_calculator = new MyCalculator();
|
||
|
|
System.out.print("I implemented: ");
|
||
|
|
ImplementedInterfaceNames(my_calculator);
|
||
|
|
Scanner sc = new Scanner(System.in);
|
||
|
|
int n = sc.nextInt();
|
||
|
|
System.out.print(my_calculator.divisor_sum(n) + "\n");
|
||
|
|
sc.close();
|
||
|
|
}
|
||
|
|
/*
|
||
|
|
* ImplementedInterfaceNames method takes an object and prints the name of the interfaces it implemented
|
||
|
|
*/
|
||
|
|
static void ImplementedInterfaceNames(Object o) {
|
||
|
|
Class[] theInterfaces = o.getClass().getInterfaces();
|
||
|
|
for (int i = 0; i < theInterfaces.length; i++) {
|
||
|
|
String interfaceName = theInterfaces[i].getName();
|
||
|
|
System.out.println(interfaceName);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|