Permutations: Difference between revisions

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@@ Line 1,046: / Line 1,046: @@
 </pre>
 =={{header|Perl 6}}==
-<lang perl6># Lexicographic order
+<lang perl6>sub next_perm ( @a is copy ) {
-sub next_perm ( @a ) {
-    # j is the largest index with a[j] < a[j+1].
     my $j = @a.end - 1;
-    $j-- while $j >= 1 and [gt] @a[ $j, $j+1 ];
+    return Nil if --$j < 0 while @a[$j] after @a[$j+1];
-    # a[k] is the smallest integer greater than a[j] to the right of a[j].
     my $aj = @a[$j];
     my $k  = @a.end;
-    $k-- while [gt] $aj, @a[$k];
+    $k-- while $aj after @a[$k];
     @a[ $j, $k ] .= reverse;
+    my $r = @a.end;
-    # This puts the tail end of permutation after jth position in
-    # increasing order.
+    my $s = $j + 1;
-    my Int $r = @a.end;
+    @a[ $r--, $s++ ] .= reverse while $r > $s;
-    my Int $s = $j + 1;
+    return @a;
-    while $r > $s {
-        @a[ $r, $s ] .= reverse;
-        $r--;
-        $s++;
-    }
 }
-my @array = < a b c >.sort;
+.say for [<a b c>], &next_perm ...^ !*;</lang>
-my $perm_count = [*] 1 .. +@array; # Factorial
-for ^$perm_count {
-    @array.say;
-    next_perm(@array);
-}
-</lang>
-Output:<pre>abc
+Output:<pre>a b c
+a c b
-acb
+b a c
-bac
+b c a
-bca
+c a b
-cab
+c b a
-cba
 </pre>