x←?1e6⍴100

   {⍺,≢⍵}⌸x
44 10132
 8  9873
39  9948
53  9826
79 10068
   …

   cmpx '{⍺,≢⍵}⌸x' '{⍺,(≢⍵)}⌸x'
 {⍺,≢⍵}⌸x   → 7.50E¯4 |     0% ⎕
 {⍺,(≢⍵)}⌸x → 1.55E¯2 | +1960% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕


   f←{(b/s),⍤0-2-/(1+⍴b),⍨b/⍳⍴b←s≠¯1↓¯1,s←{⍵[⍋⍵]}⍵}
   g←{c←(1+⌈/⍵)⍴0 ⋄ c[⍵]+←1 ⋄ (b/⍳⍴b),⍤0⊢(b←0≠c)/c}

   cmpx '{⍺,≢⍵}⌸x' 'f x' 'g x'
  {⍺,≢⍵}⌸x → 7.42E¯4 |    0% ⎕⎕⎕⎕⎕
* f x      → 2.57E¯3 | +246% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
* g x      → 3.31E¯3 | +345% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕