Package net.n1da.dev.euler

Class PE0024

java.lang.Object

net.n1da.dev.euler.core.Problem

net.n1da.dev.euler.PE0024

All Implemented Interfaces:

Solvable

public class PE0024
extends Problem

Solution for problem 24 "Lexicographic permutations" completed on Mon, 29 Jun 2015, 19:46.

Since:

14.04.2015 05:23:47

Author:

Nico Danneberg

See Also:

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

Field Summary

Fields

Modifier and Type	Field	Description
private int[]	factorials	Memory for all necessary permutations.
private java.lang.String	line	Stores the line of chars to permute.
private int	place	Stores which permutation is wanted.

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

number, title

Constructor Summary

Constructors

Constructor	Description
PE0024()	A simple constructor to set number and title.

Method Summary

Modifier and Type	Method	Description
void	prepare()	Prepares the solution of this problem by setting the line and place.
java.lang.String	solve()	This method solves the given problem by running over the factorials array to find the right positions to swap the characters.
private java.lang.String	swapChar(java.lang.String text, int oPos, int nPos)	Swaps the character at given old to the new position.

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

line

private java.lang.String line

Stores the line of chars to permute.

place

private int place

Stores which permutation is wanted.

factorials

private int[] factorials

Memory for all necessary permutations.

Constructor Detail

PE0024

public PE0024()

A simple constructor to set number and title.

Method Detail

prepare

public void prepare()

Prepares the solution of this problem by setting the line and place. Additionally the factorials array is filled matching the length of the character line.

Specified by:

prepare in interface Solvable

Overrides:

prepare in class Problem

solve

public java.lang.String solve()

This method solves the given problem by running over the factorials array to find the right positions to swap the characters.

Returns:

the one millions permutation of the given characters

See Also:

swapChar(String, int, int)

swapChar

private java.lang.String swapChar(java.lang.String text,
                                  int oPos,
                                  int nPos)

Swaps the character at given old to the new position. All chars following are moved to the right (or left).

Parameters:

text - the line of characters to be changed

oPos - the old position of the char

nPos - the new position of the char

Returns:

the changed line of characters