Added solution to problem 31

src/main/java/mattrixwv/ProjectEuler/Driver.java

@@ -17,7 +17,7 @@ public class Driver{
 	private static final ArrayList<Integer> PROBLEM_NUMBERS = new ArrayList<Integer>(Arrays.asList(0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10,
 																									  11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
 																									  21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
-																									  67));
+																									  31, 67));
 	private static enum SELECTIONS{SOLVE, DESCRIPTION, LIST, EXIT, SIZE};
 	private static final Scanner input = new Scanner(System.in);
 
@@ -138,6 +138,7 @@ public class Driver{
 			case 28 : problem = new Problem28(); break;
 			case 29 : problem = new Problem29(); break;
 			case 30 : problem = new Problem30(); break;
+			case 31 : problem = new Problem31(); break;
 			case 67 : problem = new Problem67(); break;
 		}
 		return problem;

src/main/java/mattrixwv/ProjectEuler/Problems/Problem31.java

@@ -0,0 +1,64 @@
+//ProjectEulerJava/src/main/java/mattrixwv/ProjectEuler/Problems/Problem31.java
+//Matthew Ellison
+// Created: 06-19-20
+//Modified: 06-19-20
+//How many different ways can £2 be made using any number of coins?
+//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/JavaClasses
+/*
+	Copyright (C) 2020  Matthew Ellison
+
+	This program is free software: you can redistribute it and/or modify
+	it under the terms of the GNU Lesser General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU Lesser General Public License for more details.
+
+	You should have received a copy of the GNU Lesser General Public License
+	along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+package mattrixwv.ProjectEuler.Problems;
+
+public class Problem31 extends Problem{
+	private static final int desiredValue = 200;
+	private int permutations;
+	public Problem31(){
+		super("How many different ways can 2 pounds be made using any number of coins?");
+		permutations = 0;
+	}
+	public void solve(){
+		//Start the timer
+		timer.start();
+
+		//Start with 200p and remove the necessary coins with each loop
+		for(int pound2 = desiredValue; pound2 >= 0;pound2 -= 200){
+			for(int pound1 = pound2;pound1 >= 0;pound1 -= 100){
+				for(int pence50 = pound1;pence50 >= 0;pence50 -= 50){
+					for(int pence20 = pence50;pence20 >= 0;pence20 -= 20){
+						for(int pence10 = pence20;pence10 >= 0;pence10 -= 10){
+							for(int pence5 = pence10;pence5 >= 0;pence5 -= 5){
+								for (int pence2 = pence5; pence2 >= 0; pence2 -= 2){
+									++permutations;
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+
+		//Stop the timer
+		timer.stop();
+
+		//Save the result
+		result = String.format("There are %d ways to make 2 pounds with the given denominations of coins", permutations);
+	}
+}
+
+/* Results:
+There are 73682 ways to make 2 pounds with the given denominations of coins
+It took 17.899 microseconds to solve this problem.
+*/