PPT Slide

/* reverse3( Listin, Listout ) */

reverse3( [ ] , [ ] ) .

reverse3( [ First | Rest ] , Ans ) : -

reverse3( Rest , Temp ) ,

append3( Temp , [First] , Ans ) .

| ? - reverse3( [ a , b , c , d ] , X ) .

X = [ d , c , b , a ]

How efficient is this procedure?

reverse3( [ a, b, c ], X ) caused

4 calls to reverse3 .

6 calls to append3 .