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Ethiopian multiplication: Difference between revisions
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12 tests, 12 assertions, 0 failures, 0 errors</pre>
=={{header|Scala}}==
The first and second are only slightly different and use functional style.
The third uses a for loop to yield the result.
<lang scala>
def ethiopian(i:Int, j:Int):Int=
pairIterator(i,j).filter(x=> !isEven(x._1)).map(x=>x._2).foldLeft(0){(x,y)=>x+y}
def ethiopian2(i:Int, j:Int):Int=
pairIterator(i,j).map(x=>if(isEven(x._1)) 0 else x._2).foldLeft(0){(x,y)=>x+y}
def ethiopian3(i:Int, j:Int):Int=
{
var res=0;
for((h,d) <- pairIterator(i,j) if !isEven(h)) res+=d;
res
}
def isEven(x:Int)=(x&1)==0
def halve(x:Int)=x>>>1
def double(x:Int)=x<<1
// generates pairs of values (halve,double)
def pairIterator(x:Int, y:Int)=new Iterator[(Int, Int)]
{
var i=(x, y)
def hasNext=i._1>0
def next={val r=i; i=(halve(i._1), double(i._2)); r}
}
</lang>
=={{header|Scheme}}==
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