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Self-describing numbers: Difference between revisions
Replaced by a more efficient code.
Alextretyak (talk | contribs) (Added 11l) |
(Replaced by a more efficient code.) |
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=={{header|Nim}}==
This is a brute-force algorithm. To speed-up, it uses integers instead of strings and the variable “digits” is allocated once, placed in global scope and accessed directly by the two functions (something I generally avoid). We have been able to check until 1_000_000_000.
<lang nim>import algorithm, sequtils, std/monotimes, times
var i = 0▼
while true:▼
if i < 0:▼
type Digit = 0..9
proc isSelfDescribing(n): bool =▼
var digits = newSeqOfCap[Digit](10)
for i, ch in s:▼
if s.count($i) != parseInt("" & ch):▼
proc getDigits(n: Positive) =
digits.setLen(0)
digits.add n mod 10
digits.reverse()
▲proc isSelfDescribing(n: Natural): bool =
n.getDigits()
return false
let t0 = getMonoTime()
echo n, " in ", getMonoTime() - t0
echo "\nTotal time: ", getMonoTime() - t0</lang>
{{out}}
<pre>1210 in 154 microseconds and 723 nanoseconds
2020 in 376 microseconds and 687 nanoseconds
21200 in 2 milliseconds, 804 microseconds, and 259 nanoseconds
3211000 in 165 milliseconds, 490 microseconds, and 749 nanoseconds
42101000 in 2 seconds, 89 milliseconds, 515 microseconds, and 202 nanoseconds
521001000 in 27 seconds, 712 milliseconds, 35 microseconds, and 660 nanoseconds
Total time: 52 seconds, 969 milliseconds, 578 microseconds, and 698 nanoseconds</pre>
▲for x in 0 .. 4_000_000:
▲ if isSelfDescribing(x): echo x</lang>
=={{header|ooRexx}}==
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