RosettaCodeData/Task/Self-numbers/Standard-ML/self-numbers.ml
2023-07-01 13:44:08 -04:00

25 lines
880 B
Standard ML

open List;
val rec selfNumberNr = fn NR =>
let
val rec sumdgt = fn 0 => 0 | n => Int.rem (n, 10) + sumdgt (Int.quot(n ,10));
val rec isSelf = fn ([],l1,l2) => []
| (x::tt,l1,l2) => if exists (fn i=>i=x) l1 orelse exists (fn i=>i=x) l2
then ( isSelf (tt,l1,l2)) else x::isSelf (tt,l1,l2) ;
val rec partcount = fn (n, listIn , count , selfs) =>
if count >= NR then nth (selfs, length selfs + NR - count -1)
else
let
val range = tabulate (81 , fn i => 81*n +i+1) ;
val listOut = map (fn i => i + sumdgt i ) range ;
val selfs = isSelf (range,listIn,listOut)
in
partcount ( n+1 , listOut , count+length (selfs) , selfs )
end;
in
partcount (0,[],0,[])
end;
app ((fn s => print (s ^ " ")) o Int.toString o selfNumberNr) (tabulate (50,fn i=>i+1)) ;
selfNumberNr 100000000 ;