introduce bitloops

src/main/java/puzzle/LongArrayList.java

@@ -6,8 +6,6 @@ public final class LongArrayList {
    private long[] a;
    private int    size;
    
-   public LongArrayList() { this(16); }
-   
    public LongArrayList(int initialCapacity) {
       if (initialCapacity < 0) throw new IllegalArgumentException();
       a = new long[initialCapacity];