2016 Update
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Tina Müller
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7965 changed files with 139854 additions and 31002 deletions
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{{Sorting Algorithm}}
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Sort an array of integers (of any convenient size) into ascending order using [[wp:Pancake sorting|Pancake sorting]]. In short, instead of individual elements being sorted, the only operation allowed is to "flip" one end of the list, like so:
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;Task:
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Sort an array of integers (of any convenient size) into ascending order using [[wp:Pancake sorting|Pancake sorting]].
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In short, instead of individual elements being sorted, the only operation allowed is to "flip" one end of the list, like so:
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Before:
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'''6 7 8 9''' 2 5 3 4 1
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After:
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@ -14,3 +18,4 @@ For more information on pancake sorting, see [[wp:Pancake sorting|the Wikipedia
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See also:
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* [[Number reversal game]]
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* [[Topswops]]
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<br><br>
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@ -0,0 +1,65 @@
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-- Initialisation
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math.randomseed(os.time())
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numList = {step = 0, sorted = 0}
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-- Create list of n random values
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function numList:build (n)
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self.values = {}
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for i = 1, n do self.values[i] = math.random(-100, 100) end
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end
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-- Return boolean indicating whether the list is in order
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function numList:isSorted ()
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for i = 2, #self.values do
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if self.values[i] < self.values[i - 1] then return false end
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end
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print("Finished!")
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return true
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end
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-- Display list of numbers on one line
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function numList:show ()
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if self.step == 0 then
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io.write("Initial state:\t")
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else
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io.write("After step " .. self.step .. ":\t")
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end
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for _, v in ipairs(self.values) do io.write(v .. " ") end
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print()
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end
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-- Reverse n values from the left
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function numList:reverse (n)
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local flipped = {}
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for i, v in ipairs(self.values) do
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if i > n then
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flipped[i] = v
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else
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flipped[i] = self.values[n + 1 - i]
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end
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end
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self.values = flipped
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end
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-- Perform one flip of a pancake sort
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function numList:pancake ()
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local maxPos = 1
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for i = 1, #self.values - self.sorted do
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if self.values[i] > self.values[maxPos] then maxPos = i end
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end
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if maxPos == 1 then
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numList:reverse(#self.values - self.sorted)
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self.sorted = self.sorted + 1
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else
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numList:reverse(maxPos)
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end
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self.step = self.step + 1
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end
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-- Main procedure
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numList:build(10)
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numList:show()
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repeat
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numList:pancake()
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numList:show()
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until numList:isSorted()
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@ -1,35 +1,32 @@
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/*REXX program sorts and displays an array using the pancake sort algorithm.*/
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call gen /*generate elements in the @. array.*/
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call show 'before sort' /*display the BEFORE array elements.*/
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say copies('▒',40) /*display a separator line for eyeballs*/
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call pancakeSort # /*invoke the pancake sort. Yummy. */
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call show ' after sort' /*display the AFTER array elements. */
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exit /*stick a fork in it, we're all done. */
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/*────────────────────────────────────────────────────────────────────────────*/
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flip: procedure expose @.; parse arg y
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do i=1 for (y+1)%2; ymp=y-i+1; _=@.i; @.i=@.ymp; @.ymp=_
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end /*i*/
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return
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/*────────────────────────────────────────────────────────────────────────────*/
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gen: fibs= '-55 -21 -1 -8 -8 -21 -55 0 0' /*some non─positive Fibonacci numbers, most of which are repeated. */
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/* ┌───◄ a few sorted bread primes which are primes of the form: (p-3)÷2 and 2∙p+3 */
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/* ↓ where p is a prime. Bread primes are related to sandwich and meat primes.*/
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bp=2 17 5 29 7 37 13 61 43 181 47 197 67 277 97 397 113 461 137 557 167 677 173 701 797 1117 307 1237 1597 463 1861 467
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$=bp fibs; #=words($) /*combine the two lists; get # of items*/
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/* [↓] populate the @. array with #s*/
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do j=1 for #; @.j=word($,j); end /*◄─── obtain a number from the $ list.*/
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return
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/*────────────────────────────────────────────────────────────────────────────*/
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/*REXX program sorts and displays an array using the pancake sort algorithm. */
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call gen /*generate elements in the @. array.*/
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call show 'before sort' /*display the BEFORE array elements.*/
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say copies('▒', 60) /*display a separator line for eyeballs*/
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call pancakeSort # /*invoke the pancake sort. Yummy. */
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call show ' after sort' /*display the AFTER array elements. */
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exit /*stick a fork in it, we're all done. */
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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flip: parse arg y; do i=1 for (y+1)%2; yyy=y-i+1; _=@.i; @.i=@.yyy; @.yyy=_; end
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return /*swap: ↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑ */
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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gen: fibs= '-55 -21 -1 -8 -8 -21 -55 0 0' /*some non─positive Fibonacci numbers, */
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@element=right('element',21) /* most of which are repeated.
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┌◄─┬──◄─ some paired bread primes which are of the form: (p-3)÷2 and 2∙p+3
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│ │ where p is a prime. Bread primes are related to sandwich & meat primes.
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↓ ↓ ──── ──── ───── ────── ────── ────── ────── ─────── ─────── ─────── ──────*/
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bp=2 17 5 29 7 37 13 61 43 181 47 197 67 277 97 397 113 461 137 557 167 677 173 701,
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797 1117 307 1237 1597 463 1861 467
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$=bp fibs; #=words($) /*combine the two lists; get # of items*/
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do j=1 for #; @.j=word($,j); end /*◄─── obtain a number from the $ list.*/
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return /* [↑] populate the @. array with #s*/
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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pancakeSort: procedure expose @.; parse arg N
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do N=N by -1 for N-1
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!=@.1; ?=1; do j=2 to N; if @.j<=! then iterate
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!=@.j; ?=j
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end /*j*/
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call flip ?; call flip N
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end /*N*/
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return
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/*────────────────────────────────────────────────────────────────────────────*/
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show: w=length(#) /* [↓] display elements of @. array.*/
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do k=1 for #; say ' element' right(k,w) arg(1)':' right(@.k,9); end
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return
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do N=N by -1 for N-1
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!=@.1; ?=1; do j=2 to N; if @.j<=! then iterate
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!=@.j; ?=j
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end /*j*/
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call flip ?; call flip N
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end /*N*/
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return
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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show: do k=1 for #; say @element right(k,length(#)) arg(1)':' right(@.k,9); end; return
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