September 2017 Update

Task/Sorting-algorithms-Strand-sort/Jq/sorting-algorithms-strand-sort.jq

@@ -0,0 +1,38 @@
+# merge input array with array x by comparing the heads of the arrays
+# in turn; # if both arrays are sorted, the result will be sorted:
+def merge(x):
+  length as $length
+  | (x|length) as $xl
+  | if $length == 0 then x
+    elif $xl == 0 then .
+    else
+      . as $in
+      | reduce range(0; $xl + $length) as $z
+         # state [ix, xix, ans]
+         ( [0, 0, []];
+           if .[0] < $length and
+              ((.[1] < $xl and $in[.[0]] <= x[.[1]]) or .[1] == $xl)
+           then [(.[0] + 1), .[1], (.[2] + [$in[.[0]]]) ]
+           else [.[0], (.[1] + 1), (.[2] + [x[.[1]]]) ]
+           end
+         ) | .[2]
+    end ;
+
+def strand_sort:
+  # The inner function emits [strand, remainder]
+  def strand:
+    if length <= 1 then .
+    else
+      reduce .[] as $x
+      # state: [strand, remainder]
+      ([ [], [] ];
+       if ((.[0]|length) == 0) or .[0][-1] <= $x
+       then [ (.[0] + [$x]), .[1] ]
+       else [ .[0], (.[1] + [$x]) ]
+       end )
+    end ;
+
+  if length <= 1 then .
+  else strand as $s
+    | ($s[0] | merge( $s[1] | strand_sort))
+  end ;