|
|
|
479001600 //= 12!
00:00:01.328</pre>
=={{header|PHP}}==
Full non-recursive algorithm generating permutation in reversed lexicographical order.
Taken from here: [https://habrahabr.ru/post/275331/]. It's a little bit modified algorythm of Narayana Pandit [https://en.wikipedia.org/wiki/Narayana_Pandit]. It reveres a string and works until a and b are not equal. It searches
a new permutation directly (first internal cycle) as we do it on a sheet of paper. You can use English alphabet instead of digits. Author: I. Gavryushin aka dcc0.
<lang php>
<?php
$b="0123";
$a=strrev($b);
while ($a !=$b) {
$i=1;
while($a[$i] > $a[$i-1]) {
$i++;
}
$j=0;
while($a[$j] < $a[$i]) {
$j++;
}
$c=$a[$j];
$a[$j]=$a[$i];
$a[$i]=$c;
$a=strrev(substr($a, 0, $i)).substr($a, $i);
print $a. "\n";
}
?>
</lang>
'''Output'''
<pre>
3210
2310
3120
1320
2130
1230
3201
2301
3021
0321
2031
0231
3102
1302
3012
0312
1032
0132
2103
1203
2013
0213
1023
0123
</pre>
=={{header|Perl}}==
|