Added solution to problem 27

ProjectEulerCS/ProblemSelection.cs

@@ -32,7 +32,7 @@ namespace ProjectEulerCS{
 		private static readonly List<int> _PROBLEM_NUMBERS = new List<int>()
 				{ 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, 67};
+				 20, 21, 22, 23, 24, 25, 26, 27, 67};
 		public static System.Collections.Generic.List<int> PROBLEM_NUMBERS{
 			get { return _PROBLEM_NUMBERS; }
 		}
@@ -67,6 +67,7 @@ namespace ProjectEulerCS{
 				case 24: problem = new Problem24(); break;
 				case 25: problem = new Problem25(); break;
 				case 26: problem = new Problem26(); break;
+				case 27: problem = new Problem27(); break;
 				case 67: problem = new Problem67(); break;
 			}
 			return problem;

ProjectEulerCS/Problems/Problem26.cs

@@ -2,7 +2,7 @@
 //Matthew Ellison
 // Created: 09-11-20
 //Modified: 09-11-20
-//What is the index of the first term in the Fibonacci sequence to contain 1000 digits?
+//Find the value of d < 1000 for which 1/d contains the longest recurring cycle in its decimal fraction part.
 //Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/CSClasses
 /*
 	Copyright (C) 2020  Matthew Ellison

ProjectEulerCS/Problems/Problem27.cs

@@ -0,0 +1,138 @@
+//ProjectEuler/ProjectEulerCS/src/Problems/Problem27.cs
+//Matthew Ellison
+// Created: 09-11-20
+//Modified: 09-11-20
+//Find the product of the coefficients, |a| < 1000 and |b| <= 1000, for the quadratic expression that produces the maximum number of primes for consecutive values of n, starting with n=0.
+//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/CSClasses
+/*
+	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/>.
+*/
+
+
+using System.Collections.Generic;
+
+
+namespace ProjectEulerCS.Problems{
+	public class Problem27 : Problem{
+		//Variables
+		//Static variables
+		private const int LARGEST_POSSIBLE_A = 999;
+		private const int LARGEST_POSSIBLE_B = 1000;
+		//Instance variables
+		private int topA;	//The A for the most n's generated
+		private int topB;	//THe B for the most n's generated
+		private int topN;	//The most n's generated
+		private List<int> primes;	//A list of all primes that could possibly be generated with this formula
+		public int TOP_A{
+			get{
+				if(!solved){
+					throw new Unsolved();
+				}
+				return topA;
+			}
+		}
+		public int TOP_B{
+			get{
+				if(!solved){
+					throw new Unsolved();
+				}
+				return topB;
+			}
+		}
+		public int TOP_N{
+			get{
+				if(!solved){
+					throw new Unsolved();
+				}
+				return topN;
+			}
+		}
+		public override string Result{
+			get{
+				if(!solved){
+					throw new Unsolved();
+				}
+				return $"The greatest number of primes found is {topN}\nIt was found with A = {topA}, B = {topB}\nThe product of A and B is {topA * topB}";
+			}
+		}
+
+		//Functions
+		//Constructor
+		public Problem27() : base($"Find the product of the coefficients, |a| <= {LARGEST_POSSIBLE_A} and |b| <= {LARGEST_POSSIBLE_B}, for the quadratic expression that produces the maximum number of primes for consecutive values of n, starting with n=0"){
+			topA = 0;
+			topB = 0;
+			topN = 0;
+			primes = new List<int>();
+		}
+		//Operational functions
+		//Solve the problem
+		public override void Solve(){
+			//If the problem has already been solved do nothing and end the function
+			if(solved){
+				return;
+			}
+
+			//Start the timer
+			timer.Start();
+
+			//Get the primes
+			primes = mee.Algorithms.GetPrimes(12000);
+
+			//Start with the lowest possible A and check all possibilities after that
+			for(int a = -LARGEST_POSSIBLE_A;a <= LARGEST_POSSIBLE_A;++a){
+				//Start with the lowest possible B and check all possibilities after that
+				for(int b = -LARGEST_POSSIBLE_B;b <= LARGEST_POSSIBLE_B;++b){
+					//Start with n=0 and check the formula to see how many primes you can get with concecutive n's
+					int n = 0;
+					int quadratic = (n * n) + (a * n) + b;
+					while(primes.Contains(quadratic)){
+						++n;
+						quadratic = (n * n) + (a * n) + b;
+					}
+					--n;	//Negate an n because the last formula failed'
+
+					//Set all the largest numbers if this created more primes than any other
+					if(n > topN){
+						topN = n;
+						topB = b;
+						topA = a;
+					}
+				}
+			}
+
+			//Top the timer
+			timer.Stop();
+
+			//Throw a flag to show the problem is solved
+			solved = true;
+		}
+		//Reset the problem so it can be run again
+		public override void Reset(){
+			base.Reset();
+			topA = 0;
+			topB = 0;
+			topN = 0;
+			primes.Clear();
+		}
+	}
+}
+
+/* Result:
+The greatest number of primes found is 70
+It was found with A = -61, B = 971
+The product of A and B is -59231
+It took an average of 1.394 seconds to run this problem through 100 iterations
+*/