An ugly "hurry up" implementation of NextPermutation algorithm in Mathematica

NextPermutation.nb

Vk[p_List] := 
 Module[{r = 
    DeleteCases[
     MapIndexed[If[#1[[1]] < #1[[2]], Length[p] - First[#2]] &, 
      Reverse@Partition[p, 2, 1]], Null]}, 
  If[Length[r] > 0, First[r], Null]]

Vl[p_List, k_Integer] := 
 Module[{r = 
    DeleteCases[
     MapIndexed[If[p[[k]] < #1, Length[p] - First[#2] + 1, Null] &, 
      Reverse[p]], Null]}, If[Length[r] > 0, First[r], Null]]

NextPermutation[p_List] := 
 Module[{k = Vk[p], l, vk, vl, t}, 
  If[k === Null, Null, l = Vl[p, k]; 
   If[l === Null, Null, vk = p[[k]]; vl = p[[l]]; 
    t = ReplaceAll[p, {vk -> vl, vl -> vk}]; 
    Join[t[[1 ;; k]], Reverse[t[[k + 1 ;; All]]]]]]]