Package net.n1da.dev.euler

Class PE0014

java.lang.Object

net.n1da.dev.euler.core.Problem

net.n1da.dev.euler.PE0014

All Implemented Interfaces:

Solvable

public class PE0014
extends Problem

Solution for problem 14 "Longest Collatz sequence" completed on Tue, 28 Apr 2015, 19:52.

Since:

25.04.2015 12:45:21

Author:

Nico Danneberg

See Also:

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

Field Summary

Fields

Modifier and Type	Field	Description
(package private) java.util.Hashtable<java.lang.Long,java.lang.Integer>	cache	Stores the count of terms for every starting number.

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

number, title

Constructor Summary

Constructors

Constructor	Description
PE0014()	A simple constructor to set number and title.

Method Summary

Modifier and Type	Method	Description
private int	getCount(long num)	Retrieves the count of elements in the Collatz series with the given number as starting element.
void	prepare()	The cache is created with 1.000.000 cells and initialized at the first three places: [0]=0, [1]=1, [2]=2.
java.lang.String	solve()	Runs a loop from 2 to 1.000.000 to find the maximum number of elements in a Collatz series for every loop turn.

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

java.util.Hashtable<java.lang.Long,java.lang.Integer> cache

Stores the count of terms for every starting number.

Constructor Detail

PE0014

public PE0014()

A simple constructor to set number and title.

Method Detail

prepare

public void prepare()

The cache is created with 1.000.000 cells and initialized at the first three places: [0]=0, [1]=1, [2]=2.

Specified by:

prepare in interface Solvable

Overrides:

prepare in class Problem

solve

public java.lang.String solve()

Runs a loop from 2 to 1.000.000 to find the maximum number of elements in a Collatz series for every loop turn.

Returns:

the starting number for the maximum elements

See Also:

getCount(long)

getCount

private int getCount(long num)

Retrieves the count of elements in the Collatz series with the given number as starting element. All elements found on the way to the final count are added onto the cache.

Parameters:

num - the starting number

Returns:

the count of elements in the Collatz series