Another update from ingydotnet^djgoku

Task/Ethiopian-multiplication/Java/ethiopian-multiplication-4.java

@@ -0,0 +1 @@
+def pairs: while( .[0] > 0; [ (.[0] | halve), (.[1] | double) ]);

Task/Ethiopian-multiplication/Java/ethiopian-multiplication-5.java

@@ -0,0 +1,15 @@
+def halve: (./2) | floor;
+
+def double: 2 * .;
+
+def isEven: . % 2 == 0;
+
+def ethiopian_multiply(a;b):
+  def pairs: recurse( if .[0] > 0
+                      then [ (.[0] | halve), (.[1] | double) ]
+                      else empty
+                      end );
+  reduce ([a,b] | pairs
+          | select( .[0] | isEven | not)
+          | .[1] ) as $i
+    (0; . + $i) ;

Task/Ethiopian-multiplication/Java/ethiopian-multiplication-6.java

@@ -0,0 +1 @@
+ethiopian_multiply(17;34) # => 578