Knuth shuffle: Difference between revisions

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 <lang gap># Return the list L after applying Knuth shuffle. GAP also has the function Shuffle, which does the same.
 ShuffleAlt := function(a)
-   local i, j, n, t;
+    local i, j, n, t;
-   n := Length(a);
+    n := Length(a);
-   for i in [n, n - 1 .. 2] do
+    for i in [n, n - 1 .. 2] do
-      j := Random(1, i);
+        j := Random(1, i);
-      t := a[i];
+        t := a[i];
-      a[i] := a[j];
+        a[i] := a[j];
-      a[j] := t;
+        a[j] := t;
-   od;
+    od;
-   return a;
+    return a;
 end;
 # Return a "Permutation" object (a permutation of 1 .. n).
 # They are printed in GAP, in cycle decomposition form.
-PermShuffle := n -> PermListList([1 .. n], Shuffle([1 .. n]));
+PermShuffle := n -> PermList(ShuffleAlt([1 .. n]));
 ShuffleAlt([1 .. 10]);