net.n1da.dev.euler

Class PE0021

java.lang.Object

net.n1da.dev.euler.core.Problem

net.n1da.dev.euler.PE0021

All Implemented Interfaces:

Solvable

public class PE0021
extends Problem

Solution for problem 21 "Amicable numbers" completed on Sun, 24 May 2015, 06:32.

Since:

24.05.2015 06:09:13

Author:

Nico Danneberg

See Also:

Problem @ Project Euler, Solution @ Ni-Da-Net

Field Summary

Fields

Modifier and Type	Field and Description
(package private) ArrayList<Long>	cache Stores all found amicable numbers.

Fields inherited from class net.n1da.dev.euler.core.Problem

number, title

Constructor Summary

Constructors

Constructor and Description
PE0021() A simple constructor to set number and title.

Method Summary

Modifier and Type	Method and Description
private boolean	isAmicable(int num) Checks the given number to be a amicable number.
void	prepare() Just initializes the cache as empty memory.
String	solve() Runs a loop to 10000 and checks if the current number is amicable.

Methods inherited from class net.n1da.dev.euler.core.Problem

finish, getResult, getRuntime, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

cache

ArrayList<Long> cache

Stores all found amicable numbers.

Constructor Detail

PE0021

public PE0021()

A simple constructor to set number and title.

Method Detail

prepare

public void prepare()

Just initializes the cache as empty memory.

Specified by:

prepare in interface Solvable

Overrides:

prepare in class Problem

solve

public String solve()

Runs a loop to 10000 and checks if the current number is amicable. A found amicable number is added to final sum.

Returns:

the sum of all found amicable numbers

See Also:

isAmicable(int)

isAmicable

private boolean isAmicable(int num)

Checks the given number to be a amicable number. Therefore first the cache is asked. If the number could not be found in cache the sum of divisors is calculated.

Parameters:

num - the number to be checked

Returns:

true if the number is amicable

See Also:

Mathe.getSumOfDivisors(long)