Package net.n1da.dev.euler

Class PE0061

java.lang.Object

net.n1da.dev.euler.core.Problem

net.n1da.dev.euler.PE0061

All Implemented Interfaces:

Solvable

public class PE0061
extends Problem

Solution for problem 61 "Cyclical figurate numbers" completed on Thu, 21 Mar 2019, 22:49.

Since:

06.05.2018 08:14:33

Author:

Nico Danneberg

See Also:

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

Field Summary

Fields

Modifier and Type	Field	Description
private java.util.Vector<java.util.ArrayList<java.lang.Integer>>	mem	Memory for all Triangle, Square, Pentagonal, Hexagonal, Heptagonal, and Octagonal numbers with 4 digits.

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

number, title

Constructor Summary

Constructors

Constructor	Description
PE0061()	A simple constructor to set number and title.

Method Summary

Modifier and Type	Method	Description
private boolean	check(int a, int b)	Checks if the given numbers follow each other.
private int	find()	Starts the recursion by testing every Triangle number.
private int	find(int level, int used, int first, int current)	Tries to find a number that follows the given current number.
void	prepare()	All 4 digit numbers are calculated and stored in the memory attribute.
java.lang.String	solve()	This method solves the problem bei calling find() method as starting point of recursion.

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

mem

private java.util.Vector<java.util.ArrayList<java.lang.Integer>> mem

Memory for all Triangle, Square, Pentagonal, Hexagonal, Heptagonal, and Octagonal numbers with 4 digits.

Constructor Detail

PE0061

public PE0061()

A simple constructor to set number and title.

Method Detail

prepare

public void prepare()

All 4 digit numbers are calculated and stored in the memory attribute.

Specified by:

prepare in interface Solvable

Overrides:

prepare in class Problem

solve

public java.lang.String solve()

This method solves the problem bei calling find() method as starting point of recursion.

Returns:

sum of the found six cyclic numbers

find

private int find()

Starts the recursion by testing every Triangle number.

Returns:

the found sum of the six cyclic numbers

find

private int find(int level,
                 int used,
                 int first,
                 int current)

Tries to find a number that follows the given current number. If it finds such a number it calls itself recursively with a higher level. If level 6 is reached it checks if the current number can have the first number as follower.

Parameters:

level - the current level

used - a binary number that stores all used figurate levels

first - the very first number (a Triangle)

current - the current number

Returns:

the sum of all cyclic number to the current level

check

private boolean check(int a,
                      int b)

Checks if the given numbers follow each other.

Parameters:

a - the previous number

b - the follower

Returns:

true if the last two digits of a are equal to the first two digits of b