RosettaCodeData/Task/Fusc-sequence/D/fusc-sequence-1.d

26 lines
733 B
D

import std.functional, std.stdio, std.format, std.conv;
ulong fusc(ulong n) =>
memoize!fuscImp(n);
ulong fuscImp(ulong n) =>
( n < 2 ) ? n :
( n % 2 == 0 ) ? memoize!fuscImp( n/2 ) :
memoize!fuscImp( (n-1)/2 ) + memoize!fuscImp( (n+1)/2 );
void main() {
const N_FIRST=61;
const MAX_N_DIGITS=5;
format!"First %d fusc numbers: "(N_FIRST).write;
foreach( n; 0..N_FIRST ) n.fusc.format!"%d ".write;
writeln;
format!"\nFusc numbers with more digits than any previous (1 to %d digits):"(MAX_N_DIGITS).writeln;
for(auto n=0, ndigits=0; ndigits<MAX_N_DIGITS; n++)
if( n.fusc.to!string.length > ndigits ){
format!"fusc(%d)=%d"( n, n.fusc ).writeln;
ndigits = n.fusc.to!string.length.to!int;
}
}