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Added function for SieveOfEratosthenes

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Mattrixwv
2021-06-30 12:02:13 -04:00
parent 5ac02757f4
commit 34edb993f2
2 changed files with 89 additions and 2 deletions
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67
CSClasses/Algorithms.cs
View File

@@ -1,7 +1,7 @@
//C#/CSClasses/Algorithms.cs
//Matthew Ellison
// Created: 08-23-20
//Modified: 06-29-21
//Modified: 06-30-21
//This file contains a class that is used to time the execution time of other programs
/*
Copyright (C) 2021 Matthew Ellison
@@ -836,5 +836,70 @@ namespace mee{
}
return binaryString;
}
//Sieve of Eratosthenese for generating primes
public static IEnumerable<long> SieveOfEratosthenes(){
yield return 2;
//A dictionary for holding the results of all primes that have already been found
Dictionary<long, List<long>> dict = new Dictionary<long, List<long>>();
//Start checking for primes with the number 3 and skip all even numbers
for(long possiblePrime = 3;true;possiblePrime += 2){
//If possiblePrime is not in the dictionary it is a new prime number
//Return it and mark its next multiple
if(!dict.ContainsKey(possiblePrime)){
yield return possiblePrime;
List<long> tempList = new List<long>(){possiblePrime};
dict.Add(possiblePrime * possiblePrime, tempList);
}
//If possiblePrime is in the dictionary it is a composite number
else{
//Move each witness to it's next multiple
foreach(long num in dict[possiblePrime]){
if(dict.ContainsKey(num + num + possiblePrime)){
dict[num + num + possiblePrime].Add(num);
}
else{
List<long> tempList = new List<long>(){num};
dict.Add(num + num + possiblePrime, tempList);
}
}
//We no longer need this, free the memory
dict.Remove(possiblePrime);
}
}
}
public static IEnumerable<BigInteger> SieveOfEratosthenesBig(){
yield return 2;
//A dictionary for holding the results of all primes that have already been found
Dictionary<BigInteger, List<BigInteger>> dict = new Dictionary<BigInteger, List<BigInteger>>();
//Start checking for priems with the number 3 and skip all even numbers
for(BigInteger possiblePrime = 3;true;possiblePrime += 2){
//If possiblePrime is not in the dictionary it is a new priem number
//Return it and mark its next multiple
if(!dict.ContainsKey(possiblePrime)){
yield return possiblePrime;
List<BigInteger> tempList = new List<BigInteger>(){possiblePrime};
dict.Add(possiblePrime * possiblePrime, tempList);
}
//If possiblePrime is in the dictionary it is a composite number
else{
//Move each witness to ti's next multiple
foreach(BigInteger num in dict[possiblePrime]){
if(dict.ContainsKey(num + num + possiblePrime)){
dict[num + num + possiblePrime].Add(num);
}
else{
List<BigInteger> tempList = new List<BigInteger>(){num};
dict.Add(num + num + possiblePrime, tempList);
}
}
//We no longer need this, free the memory
dict.Remove(possiblePrime);
}
}
}
}
}

24
TestCSClasses/TestAlgorithms.cs
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@@ -1,7 +1,7 @@
//C#/CSClasses/TestCSClasses/TestAlgorithms.cs
//Matthew Ellison
// Created: 03-11-21
//Modified: 06-29-21
//Modified: 06-30-21
//This file contains the tests for the Algorithms class
/*
Copyright (C) 2021 Matthew Ellison
@@ -400,5 +400,27 @@ namespace TestCSClasses{
answer = mee.Algorithms.ToBin(bigNum);
Assert.AreEqual(correctAnswer, answer, "ToBin big 3 failed");
}
[TestMethod]
public void TestSieveOfEratosthenes(){
//Test 1
IEnumerator<long> sieve = mee.Algorithms.SieveOfEratosthenes().GetEnumerator();
List<long> correctAnswer = new List<long>(){2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97};
List<long> answer = new List<long>();
for(int cnt = 0;cnt < 25;++cnt){
sieve.MoveNext();
answer.Add(sieve.Current);
}
CollectionAssert.AreEqual(correctAnswer, answer, "SieveOfEratosthenes failed");
//Test 2
IEnumerator<BigInteger> bigSieve = mee.Algorithms.SieveOfEratosthenesBig().GetEnumerator();
List<BigInteger> bigCorrectAnswer = new List<BigInteger>(){2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97};
List<BigInteger> bigAnswer = new List<BigInteger>();
for(int cnt = 0;cnt < 25;++cnt){
bigSieve.MoveNext();
bigAnswer.Add(bigSieve.Current);
}
CollectionAssert.AreEqual(bigCorrectAnswer, bigAnswer, "SieveOfEratosthenesBig failed");
}
}
}