Added Sieve of Eratosthenes implementations

src/main/java/mattrixwv/SieveOfEratosthenes.java

@@ -0,0 +1,61 @@
+package mattrixwv;
+
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+
+
+public class SieveOfEratosthenes implements Iterator<Long>{
+	long possiblePrime;
+	private Map<Long, ArrayList<Long>> dict;
+
+	public SieveOfEratosthenes(){
+		dict = new HashMap<Long, ArrayList<Long>>();
+		possiblePrime = 2;
+	}
+	@Override
+	public boolean hasNext(){
+		return true;
+	}
+	@Override
+	public Long next(){
+		long prime;
+		if(possiblePrime > 2){
+			//Loop until you find a prime number
+			for(;dict.containsKey(possiblePrime);possiblePrime += 2){
+				//Create the next entry for all entries in the map
+				for(long num : dict.get(possiblePrime)){
+					if(!dict.containsKey(possiblePrime + num + num)){
+						ArrayList<Long> tempArray = new ArrayList<Long>(Arrays.asList(num));
+						dict.put(possiblePrime + num + num, tempArray);
+					}
+					else{
+						dict.get(possiblePrime + num + num).add(num);
+					}
+				}
+				//Delete the current entry
+				dict.remove(possiblePrime);
+			}
+			//Save that the number is a prime
+			prime = possiblePrime;
+			//Add the next entry to the prime
+			if(!dict.containsKey(prime * 3)){
+				ArrayList<Long> tempArray = new ArrayList<Long>(Arrays.asList(prime));
+				dict.put(prime * 3, tempArray);
+			}
+			else{
+				dict.get(prime * 3).add(prime);
+			}
+			//Move on to the next possible prime
+			possiblePrime += 2;
+		}
+		else{
+			//Return 2 and move to 3
+			prime = possiblePrime++;
+		}
+		return prime;
+	}
+}

src/main/java/mattrixwv/SieveOfEratosthenesBig.java

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+package mattrixwv;
+
+
+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+
+
+public class SieveOfEratosthenesBig implements Iterator<BigInteger>{
+	BigInteger possiblePrime;
+	private Map<BigInteger, ArrayList<BigInteger>> dict;
+
+	public SieveOfEratosthenesBig(){
+		dict = new HashMap<BigInteger, ArrayList<BigInteger>>();
+		possiblePrime = BigInteger.TWO;
+	}
+	@Override
+	public boolean hasNext(){
+		return true;
+	}
+	@Override
+	public BigInteger next(){
+		BigInteger prime;
+		if(possiblePrime.compareTo(BigInteger.TWO) > 0){
+			//Loop until you find a prime number
+			for(;dict.containsKey(possiblePrime);possiblePrime = possiblePrime.add(BigInteger.TWO)){
+				//Create the next entry for all entries in the map
+				for(BigInteger num : dict.get(possiblePrime)){
+					BigInteger loc = possiblePrime.add(num).add(num);
+					if(!dict.containsKey(loc)){
+						ArrayList<BigInteger> tempArray = new ArrayList<BigInteger>(Arrays.asList(num));
+						dict.put(loc, tempArray);
+					}
+					else{
+						dict.get(loc).add(num);
+					}
+				}
+				//Delete the current entry
+				dict.remove(possiblePrime);
+			}
+			//Save that the number is a prime
+			prime = possiblePrime;
+			BigInteger loc = prime.multiply(BigInteger.valueOf(3));
+			if(!dict.containsKey(loc)){
+				ArrayList<BigInteger> tempArray = new ArrayList<BigInteger>(Arrays.asList(prime));
+				dict.put(loc, tempArray);
+			}
+			else{
+				dict.get(loc).add(prime);
+			}
+			//Move on to the next possible prime
+			possiblePrime = possiblePrime.add(BigInteger.TWO);
+		}
+		else{
+			//Return 2 and move to 3
+			prime = possiblePrime;
+			possiblePrime = possiblePrime.add(BigInteger.ONE);
+		}
+		return prime;
+	}
+}