Numbers in base 10 that are palindromic in bases 2, 4, and 16: Difference between revisions
Numbers in base 10 that are palindromic in bases 2, 4, and 16 (view source)
Revision as of 07:26, 14 March 2023
, 1 year ago→{{header|jq}}
Drkameleon (talk | contribs) (added Arturo) |
|||
Line 486:
0 1 3 5 15 17 51 85 255 257 273 771 819 1285 1365 3855 4095 4097 4369 12291 13107 20485 21845
</syntaxhighlight>
=={{header|jq}}==
{{works with|jq}}
'''Also works with gojq and fq, the Go implementations'''
'''With minor tweaks, also works with faq, the Rust implementation'''
This entry, which uses a stream-oriented approach to illustrate an
economical use of memory, uses `tobase` as found in the Wikipedia article on jq; it works for
bases up to 36 inclusive.
Use gojq or fq for unbounded-precision integer arithmetic.
<syntaxhighlight lang=jq>
def lpad($len): tostring | ($len - length) as $l | (" " * $l)[:$l] + .;
# nwise/2 assumes that null can be taken as the eos marker
def nwise(stream; $n):
foreach (stream, null) as $x ([];
if length == $n then [$x] else . + [$x] end;
if (.[-1] == null) and length>1 then .[:-1]
elif length == $n then .
else empty
end);
def tobase($b):
def digit: "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[.:.+1];
def mod: . % $b;
def div: ((. - mod) / $b);
def digits: recurse( select(. > 0) | div) | mod ;
# For jq it would be wise to protect against `infinite` as input, but using `isinfinite` confuses gojq
select( (tostring|test("^[0-9]+$")) and 2 <= $b and $b <= 36)
| if . == 0 then "0"
else [digits | digit] | reverse[1:] | add
end;
# boolean
def palindrome: explode as $in | ($in|reverse) == $in;
# boolean
def palindrome($b):
tobase($b) | palindrome;
def task($n):
"Numbers under \($n) in base 10 which are palindromic in bases 2, 4 and 16:",
(nwise(range(0;$n) | select(palindrome(2) and palindrome(4) and palindrome(16)); 5)
| map( lpad(6) ) | join(" "));
task(25000)
</syntaxhighlight>
{{output}}
<pre>
Numbers under 25000 in base 10 which are palindromic in bases 2, 4 and 16:
0 1 3 5 15
17 51 85 255 257
273 771 819 1285 1365
3855 4095 4097 4369 12291
13107 20485 21845
</pre>
=={{header|Julia}}==
| |||