Package net.n1da.dev.euler

Class PE0031

java.lang.Object

net.n1da.dev.euler.core.Problem

net.n1da.dev.euler.PE0031

All Implemented Interfaces:

Solvable

public class PE0031
extends Problem

Solution for problem 31 "Coin sums" completed on Sat, 19 Dec 2015, 22:30.

Since:

12.12.2015 00:23:18

Author:

Nico Danneberg

See Also:

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

Field Summary

Fields

Modifier and Type	Field	Description
private int[]	coins	Stores for every coin the count to fill 200 pence.
private int	count	Counts the number of found combinations.
private int[]	used	Stores for every coin how many are used in a combination.

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

number, title

Constructor Summary

Constructors

Constructor	Description
PE0031()	A simple constructor to set number and title.

Method Summary

Modifier and Type	Method	Description
private void	check(int level)	Here the algorithm is implemented by checking every combination of coins.
private int	getSum()	Calculates the sum of the combination in used array.
void	prepare()	Initializes the coins and used arrays, and the count with 0.
java.lang.String	solve()	This problem is solved by a recursive call of the check(int) method.

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

coins

private int[] coins

Stores for every coin the count to fill 200 pence.

used

private int[] used

Stores for every coin how many are used in a combination.

count

private int count

Counts the number of found combinations.

Constructor Detail

PE0031

public PE0031()

A simple constructor to set number and title.

Method Detail

prepare

public void prepare()

Initializes the coins and used arrays, and the count with 0.

Specified by:

prepare in interface Solvable

Overrides:

prepare in class Problem

solve

public java.lang.String solve()

This problem is solved by a recursive call of the check(int) method. Here this method is called and the final count is returned.

Returns:

the count of all found combinations

check

private void check(int level)

Here the algorithm is implemented by checking every combination of coins. If the sum of the current combination is less than 200 this method is called recursively for the next smaller coin.

Parameters:

level - the position in coins array

getSum

private int getSum()

Calculates the sum of the combination in used array.

Returns:

the sum of all products of elements in used and #coins array