Added solution to problem 37

src/main/java/mattrixwv/ProjectEuler/ProblemSelection.java

@@ -36,7 +36,7 @@ public class ProblemSelection{
 	public 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,
-																									  31, 32, 33, 34, 35, 36, 67));
+																									  31, 32, 33, 34, 35, 36, 37, 67));
 
 	//Returns the problem corresponding to the given problem number
 	public static Problem getProblem(Integer problemNumber){
@@ -78,6 +78,7 @@ public class ProblemSelection{
 			case 34 : problem = new Problem34(); break;
 			case 35 : problem = new Problem35(); break;
 			case 36 : problem = new Problem36(); break;
+			case 37 : problem = new Problem37(); break;
 			case 67 : problem = new Problem67(); break;
 		}
 		return problem;

src/main/java/mattrixwv/ProjectEuler/Problems/Problem36.java

@@ -1,4 +1,4 @@
-//ProjectEulerJava/str/main/java/mattrixwv/ProjectEuler/Problems/Problem36.java
+//ProjectEulerJava/src/main/java/mattrixwv/ProjectEuler/Problems/Problem36.java
 //Matthew Ellison
 // Created: 06-29-21
 //Modified: 06-29-21

src/main/java/mattrixwv/ProjectEuler/Problems/Problem37.java

@@ -0,0 +1,160 @@
+//ProjectEulerJava/src/main/java/mattrixwv/ProjectEuler/Problems/Problem37.java
+//Matthew Ellison
+// Created: 07-01-21
+//Modified: 07-01-21
+//Find the sum of the only eleven primes that are both truncatable from left to right and right to left (2, 3, 5, and 7 are not counted).
+//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/JavaClasses
+/*
+	Copyright (C) 2021  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;
+
+import java.util.ArrayList;
+
+import mattrixwv.Algorithms;
+import mattrixwv.SieveOfEratosthenes;
+import mattrixwv.ProjectEuler.Unsolved;
+
+public class Problem37 extends Problem{
+	//Variables
+	//Static variables
+	private static final long LAST_PRIME_BEFORE_CHECK = 7;	//The last prime before 11 since single digit primes aren't checked
+	//Instance variables
+	private ArrayList<Long> truncPrimes;	//All numbers that are truncatable primes
+	private long sum;	//The sum of all elements in truncPrimes
+
+	//Functions
+	//Constructor
+	public Problem37(){
+		super("Find the sum of the only eleven primes that are both truncatable from left to right and right to left (2, 3, 5, and 7 are not counted).");
+		truncPrimes = new ArrayList<Long>();
+		sum = 0;
+	}
+	//Operational functions
+	//Solve the problem
+	public void solve(){
+		//If the problem has already been solved do nothing and end the function
+		if(solved){
+			return;
+		}
+
+		//Start the timer
+		timer.start();
+
+		//Create the sieve and get the first prime number
+		SieveOfEratosthenes sieve = new SieveOfEratosthenes();
+		long currentPrime = sieve.next();
+		//Loop through the sieve until you get to LAST_PRIME_BEFORE_CHECK
+		while(currentPrime < LAST_PRIME_BEFORE_CHECK){
+			currentPrime = sieve.next();
+		}
+		//Loop until truncPrimes contains 11 elements
+		while(truncPrimes.size() < 11){
+			boolean isTruncPrime = true;
+			//Get the next prime
+			currentPrime = sieve.next();
+			//Convert the prime to a string
+			String primeString = Long.toString(currentPrime);
+			//If the string contains an even digit move to the next prime
+			for(int strLoc = 0;(strLoc < primeString.length()) && (isTruncPrime);++strLoc){
+				//Allow 2 to be the first digit
+				if((strLoc == 0) && (primeString.charAt(strLoc) == '2')){
+					continue;
+				}
+				switch(primeString.charAt(strLoc)){
+					case '0' :
+					case '2' :
+					case '4' :
+					case '6' :
+					case '8' : isTruncPrime = false; break;
+				}
+			}
+			//Start removing digits from the left and see if the number stays prime
+			if(isTruncPrime){
+				for(int truncLoc = 1;truncLoc < primeString.length();++truncLoc){
+					//Create a substring of the prime, removing the needed digits from the left
+					String primeSubstring = primeString.substring(truncLoc);
+					//Convert the string to an int and see if the number is still prime
+					long newPrime = Long.valueOf(primeSubstring);
+					if(!Algorithms.isPrime(newPrime)){
+						isTruncPrime = false;
+						break;
+					}
+				}
+			}
+			//Start removing digits from the right and see if the number stays prime
+			if(isTruncPrime){
+				for(int truncLoc = 1;truncLoc < primeString.length();++truncLoc){
+					//Create a substring of the prime, removing the needed digits from the right
+					String primeSubstring = primeString.substring(0, primeString.length() - truncLoc);
+					//Convert the string to an int and see if the number is still prime
+					long newPrime = Long.valueOf(primeSubstring);
+					if(!Algorithms.isPrime(newPrime)){
+						isTruncPrime = false;
+						break;
+					}
+				}
+			}
+			//If the number remained prime through all operations add it to the vector
+			if(isTruncPrime){
+				truncPrimes.add(currentPrime);
+			}
+		}
+		//Get the sum of all elements in the truncPrimes vector
+		sum = Algorithms.getLongSum(truncPrimes);
+
+		//Stop the timer
+		timer.stop();
+
+		//Throw a flag to show the porblem is solved
+		solved = true;
+	}
+	//Reset the problem so it can be run again
+	public void reset(){
+		super.reset();
+		truncPrimes.clear();
+		sum = 0;
+	}
+
+	//Gets
+	//Returns a string with the solution to the problem
+	public String getResult(){
+		//If the problem hasn't been solved throw an exception
+		if(!solved){
+			throw new Unsolved();
+		}
+		return String.format("The sum of all left and right truncatable primes is %d", sum);
+	}
+	//Returns the list of primes that can be truncated
+	public ArrayList<Long> getTruncatablePrimes(){
+		if(!solved){
+			throw new Unsolved();
+		}
+		return truncPrimes;
+	}
+	//Return the sum of all primes in truncPrimes
+	public long getSumOfPrimes(){
+		if(!solved){
+			throw new Unsolved();
+		}
+		return sum;
+	}
+}
+
+/* Results:
+The sum of all left and right truncatable primes is 748317
+It took an average of 103.829 milliseconds to run this problem through 100 iterations
+*/