a Programmer's blog

Problem 21: Evaluate the sum of all amicable pairs under 10000.

import java.util.HashMap;

class runner
{
	public static int d(int n){
		int sum = 0;
 
		for(int i = 2; i<= Math.floor(Math.sqrt(n));i++){
			if(n%i == 0){
				int div = n/i;
				if(div != i){
					sum += i; sum+=div;
				}
			}
		}
 
		return sum+1;
	}
	
	public static void main (String[] args) throws java.lang.Exception
	{
		long time = System.currentTimeMillis();
		int n = 10000;
		HashMap cache = new HashMap(); 
		
		int sum = 0;
		for(int i=1;i