September 2017 Update

Task/Sorting-algorithms-Pancake-sort/Jq/sorting-algorithms-pancake-sort-1.jq

@@ -0,0 +1,22 @@
+def pancakeSort:
+
+  def flip(i):
+    . as $in | ($in[0:i+1]|reverse) + $in[i+1:] ;
+
+  # If input is [] then return null
+  def index_of_max:
+    . as $in
+    | reduce range(1; length) as $i
+        # state: [ix, max]
+        ( [ 0, $in[0] ];
+          if $in[$i] > .[1] then [ $i, $in[$i] ] else . end )
+    | .[0] ;
+
+  reduce range(0; length) as $iup
+    (.;
+     (length - $iup - 1) as $i
+     | (.[0:$i+1] | index_of_max) as $max
+     # flip about $max and then about $i unless $i == $max
+     | if ($i == $max) then .
+       else flip($max) | flip($i)
+       end ) ;

Task/Sorting-algorithms-Pancake-sort/Jq/sorting-algorithms-pancake-sort-2.jq

@@ -0,0 +1,2 @@
+[range(0;2), null, 1.0, 0.5, [1], [2], {"b":1}, {"a":2}, range(2;4)]
+  | pancakeSort

Task/Sorting-algorithms-Pancake-sort/Jq/sorting-algorithms-pancake-sort-3.jq

@@ -0,0 +1,2 @@
+$ jq -M -c -n -f pancake_sort.jq
+[null,0,0.5,1,1,2,3,[1],[2],{"a":2},{"b":1}]