Van Eck sequence: Difference between revisions
Added Algol W
(Added Algol 68) |
(Added Algol W) |
||
Line 471:
<pre>0 0 1 0 2 0 2 2 1 6
4 7 30 25 67 225 488 0 10 136</pre>
=={{header|ALGOL W}}==
<lang algolw>begin % find elements of the Van Eck Sequence - first term is 0, following %
% terms are 0 if the previous was the first appearance of the element %
% or how far back in the sequence the last element appeared %
% sets s to the first n elements of the Van Eck sequence %
procedure VanEck ( integer array s ( * ) ; integer value n ) ;
begin
integer array pos ( 0 :: n );
for i := 1 until n do s( i ) := 0;
for i := 0 until n do pos( i ) := 0;
for i := 2 until n do begin
integer j, prev;
j := i - 1;
prev := s( j );
if pos( prev ) not = 0 then begin
% not a new element %
s( i ) := j - pos( prev )
end if_pos_prev_ne_0 ;
pos( prev ) := j
end for_j;
end VanEck ;
% construct the first 1000 terms of the sequence %
integer MAX_VAN_ECK;
MAX_VAN_ECK := 1000;
begin
integer array seq ( 1 :: MAX_VAN_ECK );
VanEck( seq, MAX_VAN_ECK );
% show the first and last 10 elements %
for i := 1 until 10 do writeon( i_w := 1, s_w := 0, " ", seq( i ) );
write();
for i := MAX_VAN_ECK - 9 until MAX_VAN_ECK do writeon( i_w := 1, s_w := 0, " ", seq( i ) );
write()
end
end.</lang>
{{out}}
<pre>
0 0 1 0 2 0 2 2 1 6
4 7 30 25 67 225 488 0 10 136
</pre>
=={{header|AppleScript}}==
| |||