package puzzle;

import java.util.Arrays;
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];
   }
   
   public int size() { return size; }
   
   public void add(long v) {
      if (size == a.length) grow();
      a[size++] = v;
   }
   
   private void grow() {
      int    newCap = a.length == 0 ? 1 : a.length * 2;
      long[] n      = new long[newCap];
      System.arraycopy(a, 0, n, 0, size);
      a = n;
   }
   public long[] toArray() { return Arrays.copyOf(a, this.size); }
}