Package net.n1da.dev.euler

Class PE0030

java.lang.Object

net.n1da.dev.euler.core.Problem

net.n1da.dev.euler.PE0030

All Implemented Interfaces:

Solvable

Direct Known Subclasses:

PE0034

public class PE0030
extends Problem

Solution for problem 30 "Digit fifth powers" completed on Fri, 11 Dec 2015, 23:34

Since:

15.10.2015 19:33:27

Author:

Nico Danneberg

See Also:

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

Field Summary

Fields

Modifier and Type	Field	Description
protected java.util.Hashtable<LargeNumber,LargeNumber>	cache	Stores the sums of the powered digits.

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

number, title

Constructor Summary

Constructors

Modifier	Constructor	Description
	PE0030()	A simple constructor to set number and title.
protected	PE0030(int num, java.lang.String tit)	A simple base constructor to set the given Problem.number and Problem.title.

Method Summary

Modifier and Type	Method	Description
protected LargeNumber	getDigitSum(LargeNumber num)	Calculates the sum of all digits of the given number.
void	prepare()	Just the cache is initialized.
java.lang.String	solve()	Beginning with 10 all numbers to 500.000 are tested, if the sum of its powered digits are equal to the number itself.

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

protected java.util.Hashtable<LargeNumber,LargeNumber> cache

Stores the sums of the powered digits. As keys the sorted digits are used.

Constructor Detail

PE0030

public PE0030()

A simple constructor to set number and title.

PE0030

protected PE0030(int num,
                 java.lang.String tit)

A simple base constructor to set the given Problem.number and Problem.title. In this special case it's needed for inheritance to PE0034.

Parameters:

num - - the number of this problem

tit - - the title of this problem

Method Detail

prepare

public void prepare()

Just the cache is initialized.

Specified by:

prepare in interface Solvable

Overrides:

prepare in class Problem

solve

public java.lang.String solve()

Beginning with 10 all numbers to 500.000 are tested, if the sum of its powered digits are equal to the number itself. To speed up the search, the cache is used to reduce the power calculations.

Returns:

the sum of all found numbers that are equals to their powered digit sum

getDigitSum

protected LargeNumber getDigitSum(LargeNumber num)

Calculates the sum of all digits of the given number. Therefore every digit is powered by 5.

Parameters:

num - a LargeNumber to calculate the sum of its digits

Returns:

the sum of the power 5 digits as new LargeNumber

See Also:

LargeNumber.sumOfDigitPowers(int)