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Comparable Pseudo-Code Representations


~ Pseudo-Code Representation # 1 ~
   let a[] represent an arbitrary list of objects to permute
   let N equal the length of a[]
   create an integer array p[] of size N+1 to control the iteration     
   initialize p[0] to 0, p[1] to 1, p[2] to 2, ..., p[N] to N
   initialize index variable i to 1
   while (i < N) do {
      decrement p[i] by 1
      let j = 0
      if i is odd, then let j = p[i]
      swap(a[j], a[i])
      let i = 1
      while (p[i] is equal to 0) do {
         let p[i] = i
         increment i by 1
      } // end while (p[i] is equal to 0)
   } // end while (i < N)


~ Pseudo-Code Representation # 2 ~
   let a[] represent an arbitrary list of objects to permute
   let N equal the length of a[]
   create an integer array p[] of size N to control the iteration       
   initialize p[0] to 0, p[1] to 1, p[2] to 2, ..., p[N-1] to N-1
   initialize index variable i to 1
   while (i < N) do {
      if (p[i] is greater than 0) then {
         decrement p[i] by 1
         let j = 0
         if i is odd, then let j = p[i]
         swap(a[j], a[i])
         let i = 1
      } // end if
      else { // (p[i] equals 0)
         let p[i] = i
         increment i by 1
      } // end else (p[i] equals 0)
   } // end while (i < N)


~ Pseudo-Code Representation # 3 ~
   let a[] represent an arbitrary list of objects to permute
   let N equal the length of a[]
   create an integer array p[] of size N+1 to control the iteration     
   initialize p[0] to 0, p[1] to 1, p[2] to 2, ..., p[N] to N
   initialize index variable i to 1
   while (i < N) do {
      decrement p[i] by 1
      let j = (i mod 2) * p[i]
      swap(a[j], a[i])
      let i = 1
      while (p[i] is equal to 0) do {
         let p[i] = i
         increment i by 1
      } // end while (p[i] is equal to 0)
   } // end while (i < N)





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