Initial data commit

Task/Humble-numbers/Java/humble-numbers.java

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+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class HumbleNumbers {
+
+    public static void main(String[] args) {
+        System.out.println("First 50 humble numbers:");
+        System.out.println(Arrays.toString(humble(50)));
+        Map<Integer,Integer> lengthCountMap = new HashMap<>();
+        BigInteger[] seq = humble(1_000_000);
+        for ( int i = 0 ; i < seq.length ; i++ ) {
+            BigInteger humbleNumber = seq[i];
+            int len = humbleNumber.toString().length();
+            lengthCountMap.merge(len, 1, (v1, v2) -> v1 + v2);
+        }
+        List<Integer> sorted = new ArrayList<>(lengthCountMap.keySet());
+        Collections.sort(sorted);
+        System.out.printf("Length  Count%n");
+        for ( Integer len : sorted ) {
+            System.out.printf("    %2s  %5s%n", len, lengthCountMap.get(len));
+        }
+    }
+
+    private static BigInteger[] humble(int n) {
+        BigInteger two = BigInteger.valueOf(2);
+        BigInteger twoTest = two;
+        BigInteger three = BigInteger.valueOf(3);
+        BigInteger threeTest = three;
+        BigInteger five = BigInteger.valueOf(5);
+        BigInteger fiveTest = five;
+        BigInteger seven = BigInteger.valueOf(7);
+        BigInteger sevenTest = seven;
+        BigInteger[] results = new BigInteger[n];
+        results[0] = BigInteger.ONE;
+        int twoIndex = 0, threeIndex = 0, fiveIndex = 0, sevenIndex = 0;
+        for ( int index = 1 ; index < n ; index++ ) {
+            results[index] = twoTest.min(threeTest).min(fiveTest).min(sevenTest);
+            if ( results[index].compareTo(twoTest) == 0 ) {
+                twoIndex++;
+                twoTest = two.multiply(results[twoIndex]);
+            }
+            if (results[index].compareTo(threeTest) == 0 ) {
+                threeIndex++;
+                threeTest = three.multiply(results[threeIndex]);
+            }
+            if (results[index].compareTo(fiveTest) == 0 ) {
+                fiveIndex++;
+                fiveTest = five.multiply(results[fiveIndex]);
+            }
+            if (results[index].compareTo(sevenTest) == 0 ) {
+                sevenIndex++;
+                sevenTest = seven.multiply(results[sevenIndex]);
+            }
+        }
+        return results;
+    }
+
+}