Added GetDivisors function

CSClasses/Algorithms.cs

@@ -460,6 +460,109 @@ namespace mee{
 			primes.Sort();
 			return primes;
 		}
+		//These functions return all the divisors of goalNumber
+		public static List<int> GetDivisors(int goalNumber){
+			List<int> divisors = new List<int>();
+			//Start by checking that ht enumber is positive
+			if(goalNumber <= 0){
+				return divisors;
+			}
+			//If the number is 1 return just itself
+			else if(goalNumber == 1){
+				divisors.Add(1);
+				return divisors;
+			}
+
+			//Start at 3 and loop through all numbers < sqrt(goalNumber) looking for a number that divides it evenly
+			double topPossibleDivisor = Math.Ceiling(Math.Sqrt(goalNumber));
+			for(int possibleDivisor = 1;possibleDivisor <= topPossibleDivisor;++possibleDivisor){
+				//If you find one add it and the number it creates to the list
+				if((goalNumber % possibleDivisor) == 0){
+					divisors.Add(possibleDivisor);
+					//Account for the pssibility of sqrt(goalNumber) being a divisor
+					if(possibleDivisor != topPossibleDivisor){
+						divisors.Add(goalNumber / possibleDivisor);
+					}
+					//Take care of a few occations where a number was added twice
+					if(divisors[divisors.Count - 1] == (possibleDivisor + 1)){
+						++possibleDivisor;
+					}
+				}
+			}
+
+			//Sort the list before returning it for neatness
+			divisors.Sort();
+			//Return the list
+			return divisors;
+		}
+		public static List<long> GetDivisors(long goalNumber){
+			List<long> divisors = new List<long>();
+			//Start by checking that ht enumber is positive
+			if(goalNumber <= 0){
+				return divisors;
+			}
+			//If the number is 1 return just itself
+			else if(goalNumber == 1){
+				divisors.Add(1);
+				return divisors;
+			}
+
+			//Start at 3 and loop through all numbers < sqrt(goalNumber) looking for a number that divides it evenly
+			double topPossibleDivisor = Math.Ceiling(Math.Sqrt(goalNumber));
+			for(long possibleDivisor = 1;possibleDivisor <= topPossibleDivisor;++possibleDivisor){
+				//If you find one add it and the number it creates to the list
+				if((goalNumber % possibleDivisor) == 0){
+					divisors.Add(possibleDivisor);
+					//Account for the pssibility of sqrt(goalNumber) being a divisor
+					if(possibleDivisor != topPossibleDivisor){
+						divisors.Add(goalNumber / possibleDivisor);
+					}
+					//Take care of a few occations where a number was added twice
+					if(divisors[divisors.Count - 1] == (possibleDivisor + 1)){
+						++possibleDivisor;
+					}
+				}
+			}
+
+			//Sort the list before returning it for neatness
+			divisors.Sort();
+			//Return the list
+			return divisors;
+		}
+		public static List<BigInteger> GetDivisors(BigInteger goalNumber){
+			List<BigInteger> divisors = new List<BigInteger>();
+			//Start by checking that ht enumber is positive
+			if(goalNumber <= 0){
+				return divisors;
+			}
+			//If the number is 1 return just itself
+			else if(goalNumber == 1){
+				divisors.Add(1);
+				return divisors;
+			}
+
+			//Start at 3 and loop through all numbers < sqrt(goalNumber) looking for a number that divides it evenly
+			double topPossibleDivisor = Math.Exp(BigInteger.Log(goalNumber) / 2);
+			for(long possibleDivisor = 1;possibleDivisor <= topPossibleDivisor;++possibleDivisor){
+				//If you find one add it and the number it creates to the list
+				if((goalNumber % possibleDivisor) == 0){
+					divisors.Add(possibleDivisor);
+					//Account for the pssibility of sqrt(goalNumber) being a divisor
+					if(possibleDivisor != topPossibleDivisor){
+						divisors.Add(goalNumber / possibleDivisor);
+					}
+					//Take care of a few occations where a number was added twice
+					if(divisors[divisors.Count - 1] == (possibleDivisor + 1)){
+						++possibleDivisor;
+					}
+				}
+			}
+
+			//Sort the list before returning it for neatness
+			divisors.Sort();
+			//Return the list
+			return divisors;
+		}
 		//These functions get a value from combining elements in an array
 		public static int GetSum(List<int> ary){
 			return ary.Sum();