Data update

Task/Jordan-P-lya-numbers/Java/jordan-p-lya-numbers.java

@@ -0,0 +1,67 @@
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.TreeSet;
+
+public final class JordanPolyaNumbers {
+
+	public static void main(String[] aArgs) {		
+		createJordanPolya();
+		
+		final long belowHundredMillion = jordanPolyaSet.floor(100_000_000L);		
+		List<Long> jordanPolya = new ArrayList<Long>(jordanPolyaSet);
+		
+		System.out.println("The first 50 Jordan-Polya numbers:");
+		for ( int i = 0; i < 50; i++ ) {
+			System.out.print(String.format("%5s%s", jordanPolya.get(i), ( i % 10 == 9 ? "\n" : "" )));
+		}
+		System.out.println();
+		
+		System.out.println("The largest Jordan-Polya number less than 100 million: " + belowHundredMillion);
+		System.out.println();
+		
+		for ( int i : List.of( 800, 1050, 1800, 2800, 3800 ) ) {
+			System.out.println("The " + i + "th Jordan-Polya number is: " + jordanPolya.get(i - 1)
+				+ " = " + toString(decompositions.get(jordanPolya.get(i - 1))));
+		}
+	}
+	
+	private static void createJordanPolya() {
+		jordanPolyaSet.add(1L);
+		Set<Long> nextSet = new TreeSet<Long>();
+		decompositions.put(1L, new TreeMap<Integer, Integer>());
+		long factorial = 1;
+		
+		for ( int multiplier = 2; multiplier <= 20; multiplier++ ) {
+			factorial *= multiplier;			
+			for ( Iterator<Long> iterator = jordanPolyaSet.iterator(); iterator.hasNext(); ) {
+				long number = iterator.next();
+				while ( number <= Long.MAX_VALUE / factorial ) {
+					long original = number;					
+					number *= factorial;					
+					nextSet.add(number);
+		      		decompositions.put(number, new TreeMap<Integer, Integer>(decompositions.get(original)));		      		
+		      		decompositions.get(number).merge(multiplier, 1, Integer::sum);
+				}
+		    }			
+			jordanPolyaSet.addAll(nextSet);
+			nextSet.clear();
+		}
+	}
+	
+	private static String toString(Map<Integer, Integer> aMap) {
+		String result = "";
+		for ( int key : aMap.keySet() ) {
+			result = key + "!" + ( aMap.get(key) == 1 ? "" :"^" + aMap.get(key) ) + " * " + result;
+		}		
+		return result.substring(0, result.length() - 3);
+	}
+
+	private static TreeSet<Long> jordanPolyaSet = new TreeSet<Long>();
+	private static Map<Long, Map<Integer, Integer>> decompositions = new HashMap<Long, Map<Integer, Integer>>();	
+
+}