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Line 28: * A routine that does not ask the user "too many" comparison questions should be used. <br><br> =={{header\|11l}}== {{trans\|Python: Sort with custom comparator}} <syntaxhighlight lang="11l">F user_cmp(String a, b) R Int(input(‘IS #6 <, ==, or > #6 answer -1, 0 or 1:’.format(a, b))) V items = ‘violet red green indigo blue yellow orange’.split(‘ ’) V ans = sorted(items, key' cmp_to_key(user_cmp)) print("\n"ans.join(‘ ’))</syntaxhighlight> {{out}} <pre> IS red <, ==, or > violet answer -1, 0 or 1:-1 IS green <, ==, or > red answer -1, 0 or 1:1 IS green <, ==, or > violet answer -1, 0 or 1:-1 IS green <, ==, or > red answer -1, 0 or 1:1 IS indigo <, ==, or > red answer -1, 0 or 1:1 IS indigo <, ==, or > violet answer -1, 0 or 1:-1 IS indigo <, ==, or > green answer -1, 0 or 1:1 IS blue <, ==, or > red answer -1, 0 or 1:1 IS blue <, ==, or > violet answer -1, 0 or 1:-1 IS blue <, ==, or > indigo answer -1, 0 or 1:-1 IS blue <, ==, or > green answer -1, 0 or 1:1 IS yellow <, ==, or > red answer -1, 0 or 1:1 IS yellow <, ==, or > violet answer -1, 0 or 1:-1 IS yellow <, ==, or > indigo answer -1, 0 or 1:-1 IS yellow <, ==, or > blue answer -1, 0 or 1:-1 IS yellow <, ==, or > green answer -1, 0 or 1:-1 IS yellow <, ==, or > red answer -1, 0 or 1:1 IS orange <, ==, or > red answer -1, 0 or 1:1 IS orange <, ==, or > violet answer -1, 0 or 1:-1 IS orange <, ==, or > indigo answer -1, 0 or 1:-1 IS orange <, ==, or > blue answer -1, 0 or 1:-1 IS orange <, ==, or > green answer -1, 0 or 1:-1 IS orange <, ==, or > yellow answer -1, 0 or 1:-1 IS orange <, ==, or > red answer -1, 0 or 1:1 red orange yellow green blue indigo violet </pre> =={{header\|Action!}}== <syntaxhighlight lang="action!">DEFINE PTR="CARD" PROC PrintArray(PTR ARRAY a BYTE size) BYTE i Put('[) FOR i=0 TO size-1 DO IF i>0 THEN Put(' ) FI Print(a(i)) OD Put(']) PutE() RETURN BYTE FUNC IsBefore(CHAR ARRAY a,b) DEFINE NO_KEY="255" DEFINE KEY_Y="43" DEFINE KEY_N="35" BYTE CH=$02FC ;Internal hardware value for last key pressed BYTE k PrintF("Is %S before %S (y/n)? ",a,b) CH=NO_KEY ;Flush the keyboard DO k=CH UNTIL k=KEY_Y OR k=KEY_N OD CH=NO_KEY ;Flush the keyboard IF k=KEY_Y THEN PrintE("yes") RETURN (1) FI PrintE("no") RETURN (0) PROC InteractiveInsertionSort(PTR ARRAY a BYTE size) INT i,j PTR value FOR i=1 TO size-1 DO value=a(i) j=i-1 WHILE j>=0 AND IsBefore(value,a(j))=1 DO a(j+1)=a(j) j==-1 OD a(j+1)=value OD RETURN PROC Main() DEFINE COUNT="7" PTR ARRAY arr(COUNT) arr(0)="violet" arr(1)="red" arr(2)="green" arr(3)="indigo" arr(4)="blue" arr(5)="yellow" arr(6)="orange" Print("Shuffled array: ") PrintArray(arr,COUNT) PutE() InteractiveInsertionSort(arr,COUNT) PutE() Print("Sorted array: ") PrintArray(arr,COUNT) RETURN</syntaxhighlight> {{out}} [https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Order_by_pair_comparisons.png Screenshot from Atari 8-bit computer] <pre> Shuffled array: [violet red green indigo blue yellow orange] Is red before violet (y/n)? yes Is green before violet (y/n)? yes Is green before red (y/n)? no Is indigo before violet (y/n)? yes Is indigo before green (y/n)? no Is blue before violet (y/n)? yes Is blue before indigo (y/n)? yes Is blue before green (y/n)? no Is yellow before violet (y/n)? yes Is yellow before indigo (y/n)? yes Is yellow before blue (y/n)? yes Is yellow before green (y/n)? yes Is yellow before red (y/n)? no Is orange before violet (y/n)? yes Is orange before indigo (y/n)? yes Is orange before blue (y/n)? yes Is orange before green (y/n)? yes Is orange before yellow (y/n)? yes Is orange before red (y/n)? no Sorted array: [red orange yellow green blue indigo violet] </pre> =={{header\|Arturo}}== <syntaxhighlight lang="rebol">lst: ["violet" "red" "green" "indigo" "blue" "yellow" "orange"] count: 0 findSpot: function [l,e][ if empty? l -> return 0 loop.with:'i l 'item [ answer: input ~"Is \|item\| greater than \|e\| [y/n]? " if answer="y" -> return i ] return dec size l ] sortedLst: new [] loop lst 'element -> insert 'sortedLst findSpot sortedLst element element print "" print ["sorted =>" sortedLst]</syntaxhighlight> {{out}} <pre>Is violet greater than red [y/n]? y Is red greater than green [y/n]? y Is green greater than indigo [y/n]? y Is indigo greater than blue [y/n]? n Is green greater than blue [y/n]? n Is red greater than blue [y/n]? y Is indigo greater than yellow [y/n]? n Is green greater than yellow [y/n]? y Is indigo greater than orange [y/n]? n Is yellow greater than orange [y/n]? y sorted => [indigo orange yellow green blue red violet]</pre> =={{header\|AutoHotkey}}== <syntaxhighlight lang="autohotkey">data := ["Violet", "Red", "Green", "Indigo", "Blue", "Yellow", "Orange"] result := [], num := 0, Questions :="" for i, Color1 in data{ found :=false if !result.count(){ result.Push(Color1) continue } for j, Color2 in result { if (color1 = color2) continue MsgBox, 262180,, % (Q := "Q" ++num " is " Color1 " > " Color2 "?") ifMsgBox, Yes Questions .= Q "`t`tYES`n" else { Questions .= Q "`t`tNO`n" result.InsertAt(j, Color1) found := true break } } if !found result.Push(Color1) } for i, color in result output .= color ", " MsgBox % Questions "`nSorted Output :`n" Trim(output, ", ") return</syntaxhighlight> {{out}} <pre>Q1 is Red > Violet? NO Q2 is Green > Red? YES Q3 is Green > Violet? NO Q4 is Indigo > Red? YES Q5 is Indigo > Green? YES Q6 is Indigo > Violet? NO Q7 is Blue > Red? YES Q8 is Blue > Green? YES Q9 is Blue > Indigo? NO Q10 is Yellow > Red? YES Q11 is Yellow > Green? NO Q12 is Orange > Red? YES Q13 is Orange > Yellow? NO Sorted Output : Red, Orange, Yellow, Green, Blue, Indigo, Violet</pre> =={{header\|C}}== Using qsort; not very efficient <syntaxhighlight lang="c">#include <stdio.h> #include <string.h> #include <stdlib.h> int interactiveCompare(const void x1, const void x2) { const char s1 = (const char * const )x1; const char s2 = (const char const )x2; static int count = 0; printf("(%d) Is %s <, ==, or > %s? Answer -1, 0, or 1: ", ++count, s1, s2); int response; scanf("%d", &response); return response; } void printOrder(const char items[], int len) { printf("{ "); for (int i = 0; i < len; ++i) printf("%s ", items[i]); printf("}\n"); } int main(void) { const char items[] = { "violet", "red", "green", "indigo", "blue", "yellow", "orange" }; qsort(items, sizeof(items)/sizeof(items), sizeof(items), interactiveCompare); printOrder(items, sizeof(items)/sizeof(items)); return 0; }</syntaxhighlight> {{out}} <pre> (1) Is violet <, ==, or > red? Answer -1, 0, or 1: 1 (2) Is violet <, ==, or > green? Answer -1, 0, or 1: 1 (3) Is red <, ==, or > green? Answer -1, 0, or 1: -1 (4) Is violet <, ==, or > indigo? Answer -1, 0, or 1: 1 (5) Is green <, ==, or > indigo? Answer -1, 0, or 1: -1 (6) Is violet <, ==, or > blue? Answer -1, 0, or 1: 1 (7) Is indigo <, ==, or > blue? Answer -1, 0, or 1: 1 (8) Is green <, ==, or > blue? Answer -1, 0, or 1: -1 (9) Is violet <, ==, or > yellow? Answer -1, 0, or 1: 1 (10) Is indigo <, ==, or > yellow? Answer -1, 0, or 1: 1 (11) Is blue <, ==, or > yellow? Answer -1, 0, or 1: 1 (12) Is green <, ==, or > yellow? Answer -1, 0, or 1: 1 (13) Is red <, ==, or > yellow? Answer -1, 0, or 1: -1 (14) Is violet <, ==, or > orange? Answer -1, 0, or 1: 1 (15) Is indigo <, ==, or > orange? Answer -1, 0, or 1: 1 (16) Is blue <, ==, or > orange? Answer -1, 0, or 1: 1 (17) Is green <, ==, or > orange? Answer -1, 0, or 1: 1 (18) Is yellow <, ==, or > orange? Answer -1, 0, or 1: 1 (19) Is red <, ==, or > orange? Answer -1, 0, or 1: -1 { red orange yellow green blue indigo violet } </pre> =={{header\|C++}}== ===C++: Binary search insertion sort=== ~~<lang cpp>#include <algorithm>~~ <syntaxhighlight lang="cpp">#include <algorithm> #include <iostream> #include <vector> Line 63 ⟶ 348: // Use a binary insertion sort to order the items. It should ask for // close to the minimum number of questions ~~reqired~~required for(auto& item : items) { Line 74 ⟶ 359: sortedItems.insert(spotToInsert, item); } PrintOrder(sortedItems); return 0; } }</syntaxhighlight> ~~</lang>~~ {{out}} <pre> Line 102 ⟶ 387: </pre> ===C++: STL sort with custom comparator=== <syntaxhighlight lang="cpp">#include <algorithm> #include <iostream> #include <vector> using namespace std; bool InteractiveCompare(const string& s1, const string& s2) { if(s1 == s2) return false; // don't ask to compare items that are the same static int count = 0; string response; cout << "(" << ++count << ") Is " << s1 << " < " << s2 << "? "; getline(cin, response); return !response.empty() && response.front() == 'y'; } void PrintOrder(const vector<string>& items) { cout << "{ "; for(auto& item : items) cout << item << " "; cout << "}\n"; } int main() { vector<string> items { "violet", "red", "green", "indigo", "blue", "yellow", "orange" }; sort(items.begin(), items.end(), InteractiveCompare); PrintOrder(items); return 0; }</syntaxhighlight> {{out}} <pre> (1) Is indigo < violet? y (2) Is orange < indigo? y (3) Is orange < indigo? y (4) Is red < indigo? y (5) Is green < indigo? y (6) Is yellow < indigo? y (7) Is blue < indigo? y (8) Is blue < indigo? y (9) Is red < orange? y (10) Is green < red? n (11) Is green < orange? n (12) Is yellow < green? y (13) Is yellow < orange? n (14) Is blue < green? n { red orange yellow green blue indigo violet } </pre> =={{header\|Commodore BASIC}}== <syntaxhighlight lang="basic">100 REM SORT BY COMPARISON 110 DIM IN$(6), OU$(6) 120 FOR I=0 TO 6:READ IN$(I): NEXT I 130 DATA VIOLET,RED,GREEN,INDIGO,BLUE,YELLOW,ORANGE 140 OU$(0)=IN$(0):N=1 150 FOR I=1 TO 6 160 : IN$=IN$(I) 180 : GOSUB 390 190 : FOR J=0 TO N-1 200 : OU$ = OU$(J) 210 : GOSUB 340 220 : IF R>=0 THEN 280 230 : FOR K=N TO J+1 STEP -1 240 : OU$(K) = OU$(K-1) 250 : NEXT K 260 : OU$(J) = IN$ 270 : GOTO 300 280 : NEXT J 290 : OU$(N) = IN$ 300 : N=N+1 310 NEXT I 320 GOSUB 390 330 END 340 PRINT "IS "IN$" < "OU$"? (Y/N)"; 350 GET K$: IF K$<>"Y" AND K$<>"N" THEN 350 360 PRINT K$ 370 R = K$="Y" 380 RETURN 390 PRINT "("; 400 IF N=1 THEN 420 410 FOR Q=0 TO N-2:PRINT OU$(Q)",";:NEXT Q 420 PRINT OU$(N-1)")" 430 RETURN</syntaxhighlight> {{Out}} <pre> IS RED < VIOLET? (Y/N)Y IS GREEN < RED? (Y/N)N IS GREEN < VIOLET? (Y/N)Y IS INDIGO < RED? (Y/N)N IS INDIGO < GREEN? (Y/N)N IS INDIGO < VIOLET? (Y/N)Y IS BLUE < RED? (Y/N)N IS BLUE < GREEN? (Y/N)N IS BLUE < INDIGO? (Y/N)Y IS YELLOW < RED? (Y/N)N IS YELLOW < GREEN? (Y/N)Y IS ORANGE < RED? (Y/N)N IS ORANGE < YELLOW? (Y/N)Y (RED,ORANGE,YELLOW,GREEN,BLUE,INDIGO,VIOLET)</pre> =={{header\|F_Sharp\|F#}}== This task uses [https://rosettacode.org/wiki/Factorial_base_numbers_indexing_permutations_of_a_collection#F.23 Factorial base numbers indexing permutations of a collection (F#)] ~~{{incorrect\|F_Sharp\|Does not prompt user}}~~ <~~lang~~syntaxhighlight lang="fsharp"> // Order by pair comparisons. Nigel Galloway: April 23rd., 2021 let clrs=let n=System.Random() in lN2p [\|for g in 7..-1..2->n.Next(g)\|] [\|"Red";"Orange";"Yellow";"Green";"Blue";"Indigo";"Violet"\|] ~~type colours= Violet \|Red \|Green \|Indigo \|Blue \|Yellow \|Orange~~ let rec fG n g=printfn "Is %s less than %s" n g; match System.Console.ReadLine() with "Yes"-> -1\|"No"->1 \|_->printfn "Enter Yes or No"; fG n g ~~let fN,fG=let mutable z=0 in ((fun()->z),(fun n g->z<-z+1; compare n g))~~ let mutable z=0 in printfn "~~[Red;Orange;Yellow;Green;Blue;Indigo;Violet]~~%A sorted to %A using %d ~~comparisons~~questions" clrs (~~[Red;Orange;Yellow;Green;Blue;Indigo;Violet]~~clrs\|>~~List~~Array.sortWith(fun n g->z<-z+1; fG n g)) ~~(fN())~~z </syntaxhighlight> ~~</lang>~~ {{out}} Possible interaction: <pre> Is Indigo less than Orange ~~[Red;Orange;Yellow;Green;Blue;Indigo;Violet] sorted to [Violet; Red; Green; Indigo; Blue; Yellow; Orange] using 25 comparisons~~ Yes Is Blue less than Orange Yes Is Blue less than Indigo No Is Yellow less than Orange Yes Is Yellow less than Blue No Is Red less than Orange Yes Is Red less than Yellow Yes Is Red less than Blue Yes Is Red less than Indigo Yes Is Green less than Orange Yes Is Green less than Yellow Yes Is Green less than Blue Yes Is Green less than Indigo Yes Is Green less than Red No Is Violet less than Orange Yes Is Violet less than Yellow Yes Is Violet less than Blue Yes Is Violet less than Indigo Yes Is Violet less than Green Yes Is Violet less than Red Yes [\|"Orange"; "Indigo"; "Blue"; "Yellow"; "Red"; "Green"; "Violet"\|] sorted to [\|"Violet"; "Red"; "Green"; "Indigo"; "Blue"; "Yellow"; "Orange"\|] using 20 questions </pre> Line 119 ⟶ 549: Asking the user for an ordering specifier inside a custom comparator: {{works with\|Factor\|0.99 2021-02-05}} <~~lang~~syntaxhighlight lang="factor">USING: formatting io kernel math.order prettyprint qw sorting ; qw{ violet red green indigo blue yellow orange } [ "Is %s > %s? (y/n) " printf readln "y" = +gt+ +lt+ ? ] sort .</~~lang~~syntaxhighlight> {{out}} <pre> Line 139 ⟶ 569: { "red" "orange" "yellow" "green" "blue" "indigo" "violet" } </pre> =={{header\|FreeBASIC}}== {{trans\|Commodore BASIC}} <syntaxhighlight lang="freebasic"> Dim Shared As Byte r, n = 1 Dim Shared As String IN1, OU1 Dim Shared As String IN(6), OU(6) Dim As Byte i, j, k For i = 0 To 6 : Read IN(i) : Next i Data "violet", "red", "green", "indigo", "blue", "yellow", "orange" OU(0) = IN(0) Sub PrintOrder Print : Print "{"; If n = 1 Then Print OU(n-1);")" : Exit Sub For q As Byte = 0 To n-2 Print OU(q);", "; Next q Print OU(n-1);"}" End Sub Sub InteractiveCompare Dim As String1 T Print "Es "; IN1; " < "; OU1; "? (S/N) "; Do: T = Inkey$: Loop Until T <> "" If Instr("snSN", T) Then Print Ucase(T) r = T = "S" End Sub For i = 1 To 6 IN1 = IN(i) For j = 0 To n-1 OU1 = OU(j) InteractiveCompare If r < 0 Then For k = n To j+1 Step -1 OU(k) = OU(k-1) Next k OU(j) = IN1 n += 1 Exit For, For End If Next j OU(n) = IN1 n += 1 Next i PrintOrder Sleep </syntaxhighlight> =={{header\|Go}}== ===Go: Binary search insertion sort=== <syntaxhighlight lang="go">package main import ( "fmt" "sort" "strings" ) var count int = 0 func interactiveCompare(s1, s2 string) bool { count++ fmt.Printf("(%d) Is %s < %s? ", count, s1, s2) var response string _, err := fmt.Scanln(&response) return err == nil && strings.HasPrefix(response, "y") } func main() { items := []string{"violet", "red", "green", "indigo", "blue", "yellow", "orange"} var sortedItems []string // Use a binary insertion sort to order the items. It should ask for // close to the minimum number of questions required for _, item := range items { fmt.Printf("Inserting '%s' into %s\n", item, sortedItems) // sort.Search performs the binary search using interactiveCompare to // rank the items spotToInsert := sort.Search(len(sortedItems), func(i int) bool { return interactiveCompare(item, sortedItems[i]) }) sortedItems = append(sortedItems[:spotToInsert], append([]string{item}, sortedItems[spotToInsert:]...)...) } fmt.Println(sortedItems) }</syntaxhighlight> {{out}} <pre> Inserting 'violet' into [] Inserting 'red' into [violet] (1) Is red < violet? y Inserting 'green' into [red violet] (2) Is green < violet? y (3) Is green < red? n Inserting 'indigo' into [red green violet] (4) Is indigo < green? n (5) Is indigo < violet? y Inserting 'blue' into [red green indigo violet] (6) Is blue < indigo? y (7) Is blue < green? n Inserting 'yellow' into [red green blue indigo violet] (8) Is yellow < blue? y (9) Is yellow < green? y (10) Is yellow < red? n Inserting 'orange' into [red yellow green blue indigo violet] (11) Is orange < blue? y (12) Is orange < yellow? y (13) Is orange < red? n [red orange yellow green blue indigo violet] </pre> ===Go: Standard sort with custom comparator=== <syntaxhighlight lang="go">package main import ( "fmt" "sort" "strings" ) var count int = 0 type sortable []string func (s sortable) Len() int { return len(s) } func (s sortable) Swap(i, j int) { s[i], s[j] = s[j], s[i] } func (s sortable) Less(i, j int) bool { s1, s2 := s[i], s[j] count++ fmt.Printf("(%d) Is %s < %s? ", count, s1, s2) var response string _, err := fmt.Scanln(&response) return err == nil && strings.HasPrefix(response, "y") } func main() { items := sortable{"violet", "red", "green", "indigo", "blue", "yellow", "orange"} sort.Sort(items) fmt.Println(items) }</syntaxhighlight> {{out}} <pre> (1) Is orange < violet? y (2) Is red < orange? y (3) Is green < orange? n (4) Is indigo < green? n (5) Is blue < indigo? y (6) Is blue < green? n (7) Is yellow < indigo? y (8) Is yellow < blue? y (9) Is yellow < green? y (10) Is yellow < orange? n (11) Is violet < indigo? n [red orange yellow green blue indigo violet] </pre> =={{header\|Haskell}}== Injection of interaction with user is not straight-forward in pure functional language. In Haskell we use monads in order to abstract the computation flow and side effects. Fortunately the monadlist library [[https://hackage.haskell.org/package/monadlist]] contains monadic variants of most popular list operations so that it becomes easy to implement our favorite sorting algorithms. <syntaxhighlight lang="haskell">import Control.Monad import Control.Monad.ListM (sortByM, insertByM, partitionM, minimumByM) import Data.Bool (bool) import Data.Monoid import Data.List -------------------------------------------------------------------------------- isortM, msortM, tsortM :: Monad m => (a -> a -> m Ordering) -> [a] -> m [a] -- merge sort from the Control.Monad.ListM library msortM = sortByM -- insertion sort isortM cmp = foldM (flip (insertByM cmp)) [] -- tree sort aka qsort (which is not) tsortM cmp = go where go [] = pure [] go (h:t) = do (l, g) <- partitionM (fmap (LT /=) . cmp h) t go l <+> pure [h] <+> go g (<+>) = liftM2 (++)</syntaxhighlight> Now we can sort lists with effects. For example, we may count number of comparisons, using writer monad: <pre>Main> let countComparisons cmp a b = (Sum 1, a `cmp` b) Main> msortM (countComparisons compare) [2,6,3,5,9,1,5] (Sum {getSum = 15},[1,2,3,5,5,6,9]) Main> isortM (countComparisons compare) [2,6,3,5,9,1,5] (Sum {getSum = 15},[1,2,3,5,5,6,9]) Main> tsortM (countComparisons compare) [2,6,3,5,9,1,5] (Sum {getSum = 13},[1,2,3,5,5,6,9])</pre> Or use a "database" as a reference for sorting, using reader monad <pre>let fromList a b l = elemIndex a l `compare` elemIndex b l Main> msortM fromList [2,1,3,2,4,4,5,11,2,3,2,3] [1..] [1,2,2,2,2,3,3,3,4,4,5,11]</pre> Or even generate all possible permutations of a list making comparisons ambiguous: <pre>Main> isortM (\_ _ -> [LT, GT]) [1,2,3] [[1,2,3],[1,3,2],[3,1,2],[2,1,3],[2,3,1],[3,2,1]]</pre> We are ready to ask user to compare entries for us: <syntaxhighlight lang="haskell">ask a b = do putStr $ show a ++ " ≤ " ++ show b ++ " ? [y/n] " bool GT LT . ("y" ==) <$> getLine colors = ["Violet", "Red", "Green", "Indigo", "Blue", "Yellow", "Orange"]</syntaxhighlight> <pre>Main> isortM ask colors "Red" ≤ "Violet" ? [y/n] y "Green" ≤ "Red" ? [y/n] n "Green" ≤ "Violet" ? [y/n] y "Indigo" ≤ "Red" ? [y/n] n "Indigo" ≤ "Green" ? [y/n] n "Indigo" ≤ "Violet" ? [y/n] y "Blue" ≤ "Red" ? [y/n] n "Blue" ≤ "Green" ? [y/n] n "Blue" ≤ "Indigo" ? [y/n] y "Yellow" ≤ "Red" ? [y/n] n "Yellow" ≤ "Green" ? [y/n] y "Orange" ≤ "Red" ? [y/n] n "Orange" ≤ "Yellow" ? [y/n] y ["Red","Orange","Yellow","Green","Blue","Indigo","Violet"] Main> msortM ask colors "Violet" ≤ "Red" ? [y/n] n "Red" ≤ "Green" ? [y/n] y "Green" ≤ "Indigo" ? [y/n] y "Indigo" ≤ "Blue" ? [y/n] n "Blue" ≤ "Yellow" ? [y/n] n "Yellow" ≤ "Orange" ? [y/n] n "Red" ≤ "Green" ? [y/n] y "Violet" ≤ "Green" ? [y/n] n "Violet" ≤ "Indigo" ? [y/n] n "Red" ≤ "Orange" ? [y/n] y "Green" ≤ "Orange" ? [y/n] n "Green" ≤ "Yellow" ? [y/n] n "Green" ≤ "Blue" ? [y/n] y "Indigo" ≤ "Blue" ? [y/n] n ["Red","Orange","Yellow","Green","Blue","Indigo","Violet"] Main> tsortM ask colors "Violet" ≤ "Red" ? [y/n] n "Violet" ≤ "Green" ? [y/n] n "Violet" ≤ "Indigo" ? [y/n] n "Violet" ≤ "Blue" ? [y/n] n "Violet" ≤ "Yellow" ? [y/n] n "Violet" ≤ "Orange" ? [y/n] n "Red" ≤ "Green" ? [y/n] y "Red" ≤ "Indigo" ? [y/n] y "Red" ≤ "Blue" ? [y/n] y "Red" ≤ "Yellow" ? [y/n] y "Red" ≤ "Orange" ? [y/n] y "Green" ≤ "Indigo" ? [y/n] y "Green" ≤ "Blue" ? [y/n] y "Green" ≤ "Yellow" ? [y/n] n "Green" ≤ "Orange" ? [y/n] n "Yellow" ≤ "Orange" ? [y/n] n "Indigo" ≤ "Blue" ? [y/n] n ["Red","Orange","Yellow","Green","Blue","Indigo","Violet"]</pre> It seems that insertion sort with 13 comparisons is the best one, and tree sort which needed 17 questions is the worst. But efficiency of sorting depends on the order of given list. Simple statistics could be made to compare these three methods for all possible permutations of seven elements. <syntaxhighlight lang="haskell">test method = do mapM_ showHist $ hist res putStrLn $ "Median number of comparisons: " ++ show (median res) putStrLn $ "Mean number of comparisons: " ++ show (mean res) where res = getSum . fst . method cmp <$> permutations [1..7] cmp a b = (Sum 1, compare a b) median lst = sort lst !! (length lst `div` 2) mean lst = sum (fromIntegral <$> lst) / genericLength lst hist lst = (\x -> (head x, length x)) <$> group (sort lst) showHist (n, l) = putStrLn line where line = show n ++ "\t" ++ bar ++ " " ++ show perc ++ "%" bar = replicate (max perc 1) '' perc = (100 l) `div` product [1..7]</syntaxhighlight> Comparing these three methods gives that for random inputs tree sort is the best choice. <pre>Main> test msortM 6 0% 7 * 0% 8 * 0% 9 * 0% 10 * 1% 11 * 3% 12 *** 7% 13 **** 8% 14 ************ 16% 15 ******************** 24% 16 ******************** 24% 17 ********** 12% Median number of comparisons: 15 Mean number of comparisons: 14.693055555555556 Main> test isortM 6 0% 7 * 0% 8 * 0% 9 * 1% 10 * 3% 11 * 5% 12 **** 8% 13 ****** 10% 14 ******** 12% 15 ********* 13% 16 ********* 13% 17 ******* 11% 18 **** 8% 19 * 5% 20 * 3% 21 * 1% Median number of comparisons: 15 Mean number of comparisons: 14.907142857142857 Main> test tsortM 10 1% 11 ****************** 20% 12 **************** 20% 13 ************* 17% 14 **** 8% 15 ********* 13% 16 * 5% 17 ** 6% 18 2% 19 * 1% 20 * 0% 21 * 1% Median number of comparisons: 13 Mean number of comparisons: 13.485714285714286</pre> =={{header\|J}}== Implementation (here we assume that ordering is transitive):<syntaxhighlight lang="j">require'general/misc/prompt' sel=: {{ u#[ }} quicksort=: {{ if. 1 >: #y do. y else. (u quicksort y u sel e),(y =sel e),u quicksort y u~ sel e=.y{~?#y end. }} ptc=: {{ t=. (+. +./ ..~)^:_ y=1 j=. I.,t+.\|:t ($y)$(j{,t) j} ,y }} askless=: {{ coord=. x ,&(items&i.) y lt=. LT {~<coord if. 1<lt do. lt=. 'y' e. tolower prompt 'Is ',(":;x),' less than ',(":;y),'? ' LT=: ptc (lt,-.lt) (coord;\|.coord)} LT end. lt }}"0 asksort=: {{ items=: ~.y LT=: <:%=i.#items askless quicksort y }}</syntaxhighlight> Task example:<syntaxhighlight lang="j"> asksort&.;:' violet red green indigo blue yellow orange' Is indigo less than violet? yes Is indigo less than red? no Is indigo less than green? no Is indigo less than blue? no Is indigo less than yellow? no Is indigo less than orange? no Is yellow less than red? no Is yellow less than green? yes Is yellow less than blue? yes Is yellow less than orange? no Is green less than blue? yes Is red less than orange? yes red orange yellow green blue indigo violet</syntaxhighlight> =={{header\|Java}}== ===Java: Binary search insertion sort=== <syntaxhighlight lang="java">import java.util.; public class SortComp1 { public static void main(String[] args) { List<String> items = Arrays.asList("violet", "red", "green", "indigo", "blue", "yellow", "orange"); List<String> sortedItems = new ArrayList<>(); Comparator<String> interactiveCompare = new Comparator<String>() { int count = 0; Scanner s = new Scanner(System.in); public int compare(String s1, String s2) { System.out.printf("(%d) Is %s <, =, or > %s. Answer -1, 0, or 1: ", ++count, s1, s2); return s.nextInt(); } }; for (String item : items) { System.out.printf("Inserting '%s' into %s\n", item, sortedItems); int spotToInsert = Collections.binarySearch(sortedItems, item, interactiveCompare); // when item does not equal an element in sortedItems, // it returns bitwise complement of insertion point if (spotToInsert < 0) spotToInsert = ~spotToInsert; sortedItems.add(spotToInsert, item); } System.out.println(sortedItems); } }</syntaxhighlight> {{out}} <pre> Inserting 'violet' into [] Inserting 'red' into [violet] (1) Is violet <, =, or > red. Answer -1, 0, or 1: 1 Inserting 'green' into [red, violet] (2) Is red <, =, or > green. Answer -1, 0, or 1: -1 (3) Is violet <, =, or > green. Answer -1, 0, or 1: 1 Inserting 'indigo' into [red, green, violet] (4) Is green <, =, or > indigo. Answer -1, 0, or 1: -1 (5) Is violet <, =, or > indigo. Answer -1, 0, or 1: 1 Inserting 'blue' into [red, green, indigo, violet] (6) Is green <, =, or > blue. Answer -1, 0, or 1: -1 (7) Is indigo <, =, or > blue. Answer -1, 0, or 1: 1 Inserting 'yellow' into [red, green, blue, indigo, violet] (8) Is blue <, =, or > yellow. Answer -1, 0, or 1: 1 (9) Is red <, =, or > yellow. Answer -1, 0, or 1: -1 (10) Is green <, =, or > yellow. Answer -1, 0, or 1: 1 Inserting 'orange' into [red, yellow, green, blue, indigo, violet] (11) Is green <, =, or > orange. Answer -1, 0, or 1: 1 (12) Is red <, =, or > orange. Answer -1, 0, or 1: -1 (13) Is yellow <, =, or > orange. Answer -1, 0, or 1: 1 [red, orange, yellow, green, blue, indigo, violet] </pre> ===Java: Standard sort with custom comparator=== <syntaxhighlight lang="java">import java.util.; public class OrderByPair { public static void main(String[] args) { List<String> items = Arrays.asList("violet", "red", "green", "indigo", "blue", "yellow", "orange"); Collections.sort(items, new Comparator<String>() { int count = 0; Scanner s = new Scanner(System.in); public int compare(String s1, String s2) { System.out.printf("(%d) Is %s <, =, or > %s. Answer -1, 0, or 1: ", ++count, s1, s2); return s.nextInt(); } }); System.out.println(items); } }</syntaxhighlight> {{out}} <pre> (1) Is red <, =, or > violet. Answer -1, 0, or 1: -1 (2) Is green <, =, or > red. Answer -1, 0, or 1: 1 (3) Is green <, =, or > violet. Answer -1, 0, or 1: -1 (4) Is green <, =, or > red. Answer -1, 0, or 1: 1 (5) Is indigo <, =, or > green. Answer -1, 0, or 1: 1 (6) Is indigo <, =, or > violet. Answer -1, 0, or 1: -1 (7) Is blue <, =, or > indigo. Answer -1, 0, or 1: -1 (8) Is blue <, =, or > green. Answer -1, 0, or 1: 1 (9) Is yellow <, =, or > blue. Answer -1, 0, or 1: -1 (10) Is yellow <, =, or > green. Answer -1, 0, or 1: -1 (11) Is yellow <, =, or > red. Answer -1, 0, or 1: 1 (12) Is orange <, =, or > blue. Answer -1, 0, or 1: -1 (13) Is orange <, =, or > yellow. Answer -1, 0, or 1: 1 (14) Is orange <, =, or > green. Answer -1, 0, or 1: 1 [red, yellow, green, orange, blue, indigo, violet] </pre> =={{header\|jq}}== {{trans\|Wren}} {{works with\|jq}} '''Works with gojq, the Go implementation of jq''' In order for a jq program to interact with a user, prompts must be directed to stderr, which currently means that the prompt string will be printed with quotation marks. <syntaxhighlight lang="jq">def inputOption($prompt; $options): def r: $prompt \| stderr \| input as $in \| if $in\|test($options) then $in else r end; r; # Inserts item $x in the array input, which is kept sorted as per user input # assuming it is already sorted. $q is the prompt number. # Input: [$q; $a] # Output: [$qPrime, $aPrime] def insortRight($x): . as [$q, $a] \| { lo: 0, hi: ($a\|length), $q } \| until( .lo >= .hi; ( ((.lo + .hi)/2)\|floor) as $mid \| .q += 1 \| "\(.q): Is \($x) less than \($a[$mid])? y/n: " as $prompt \| (inputOption($prompt; "[yn]") == "y") as $less \| if ($less) then .hi = $mid else .lo = $mid + 1 end) # insert at position .lo \| [ .q, ($a[: .lo] + [x] + $a[.lo :]) ]; def order: reduce .[] as $item ( [0, []]; insortRight($item) ) \| .[1]; ["violet red green indigo blue yellow orange"\|splits(" ")] \| order as $ordered \| ("\nThe colors of the rainbow, in sorted order, are:", $ordered )</syntaxhighlight> '''Recommended Invocation Options''': -nRrc '''Sample Transcript''' <pre> "1: Is red less than violet? y/n: "y y "2: Is green less than violet? y/n: "y y "3: Is green less than red? y/n: "n n "4: Is indigo less than green? y/n: "n n "5: Is indigo less than violet? y/n: "y y "6: Is blue less than indigo? y/n: "y y "7: Is blue less than green? y/n: "n n "8: Is yellow less than blue? y/n: "y y "9: Is yellow less than green? y/n: "y y "10: Is yellow less than red? y/n: "n n "11: Is orange less than blue? y/n: "y y "12: Is orange less than yellow? y/n: "y y "13: Is orange less than red? y/n: "n n The colors of the rainbow, in sorted order, are: ["red","orange","yellow","green","blue","indigo","violet"] </pre> =={{header\|Julia}}== <~~lang~~syntaxhighlight lang="julia">const nrequests = [0] const ordering = Dict("violet" => 7, "red" => 1, "green" => 4, "indigo" => 6, "blue" => 5, "yellow" => 3, "orange" => 2) Line 181 ⟶ 1,164: println("Unsorted: $words") println("Sorted: $(orderbypair!(words)). Total requests: $(nrequests[1]).") </~~lang~~syntaxhighlight>{{out}} <pre> Is violet greater than indigo? (Y/N) => y Line 198 ⟶ 1,181: Is indigo greater than violet? (Y/N) => n Sorted: ["red", "orange", "yellow", "green", "blue", "indigo", "violet"]. Total requests: 14. </pre> =={{header\|Lua}}== <syntaxhighlight lang="lua">colors = { "violet", "red", "green", "indigo", "blue", "yellow", "orange" } print("unsorted: " .. table.concat(colors," ")) known, notyn, nc, nq = {}, {n="y",y="n"}, 0, 0 table.sort(colors, function(a,b) nc = nc + 1 if not known[a] then known[a]={[a]="n"} end if not known[b] then known[b]={[b]="n"} end if not (known[a][b] or known[b][a]) then io.write("Is '" .. a .. "' < '" .. b .."'? (y/n): ") nq, known[a][b] = nq+1, io.read() if a~=b then known[b][a] = notyn[known[a][b]] end end return known[a][b]=="y" end) print("sorted: " .. table.concat(colors," ")) print("(" .. nq .. " questions needed to resolve " .. nc .. " comparisons)")</syntaxhighlight> {{out}} <pre>unsorted: violet red green indigo blue yellow orange Is 'orange' < 'violet'? (y/n): y Is 'indigo' < 'orange'? (y/n): n Is 'violet' < 'indigo'? (y/n): n Is 'red' < 'indigo'? (y/n): y Is 'green' < 'indigo'? (y/n): y Is 'yellow' < 'indigo'? (y/n): y Is 'blue' < 'indigo'? (y/n): y Is 'blue' < 'orange'? (y/n): n Is 'green' < 'orange'? (y/n): n Is 'blue' < 'green'? (y/n): n Is 'red' < 'green'? (y/n): y Is 'yellow' < 'green'? (y/n): y Is 'yellow' < 'orange'? (y/n): n Is 'red' < 'orange'? (y/n): y sorted: red orange yellow green blue indigo violet (14 questions needed to resolve 18 comparisons)</pre> =={{header\|Mathematica}} / {{header\|Wolfram Language}}== <syntaxhighlight lang="mathematica">ClearAll[HumanOrderCheck] HumanOrderCheck[opt1_,opt2_]:=ChoiceDialog[Row@{"Is {",opt1,", ", opt2, "} ordered?"},{"Yes"->True,"No"->False}] Sort[{"violet","red","green","indigo","blue","yellow","orange"},HumanOrderCheck]</syntaxhighlight> {{out}} After some Yes/No clicks you should get: <pre>{"red", "orange", "yellow", "green", "blue", "indigo", "violet"}</pre> =={{header\|MiniScript}}== <syntaxhighlight lang="miniscript"> insertSort = function(arr, item) lo = 0 hi = arr.len while lo < hi mid = floor((lo + hi) / 2) ans = input("Is " + item + " less than " + arr[mid] + "? y/n: ") ans = ans[0].lower if ans == "y" then hi = mid else lo = mid + 1 end if end while arr.insert(lo, item) end function items = "violet red green indigo blue yellow orange".split ordered = [] for item in items insertSort(ordered, item) end for print ordered </syntaxhighlight> {{out}} <pre> Is red less than violet? y/n: y Is green less than violet? y/n: y Is green less than red? y/n: n Is indigo less than green? y/n: n Is indigo less than violet? y/n: y Is blue less than indigo? y/n: y Is blue less than green? y/n: n Is yellow less than blue? y/n: y Is yellow less than green? y/n: y Is yellow less than red? y/n: n Is orange less than blue? y/n: y Is orange less than yellow? y/n: y Is orange less than red? y/n: n ["red", "orange", "yellow", "green", "blue", "indigo", "violet"] </pre> =={{header\|Nim}}== Using a list filled by binary insertion and a custom comparison function. <syntaxhighlight lang="nim">import algorithm, strformat, strutils let list = ["violet", "red", "green", "indigo", "blue", "yellow", "orange"] var count = 0 proc comp(x, y: string): int = if x == y: return 0 inc count while true: stdout.write &"{count:>2}) Is {x} less than {y} (y/n)? " let answer = stdin.readLine()[0] case answer of 'y': return -1 of 'n': return 1 else: echo "Incorrect answer." var sortedList: seq[string] for elem in list: sortedList.insert(elem, sortedList.upperBound(elem, comp)) echo "Sorted list: ", sortedList.join(", ")</syntaxhighlight> {{out}} <pre> 1) Is violet less than red (y/n)? n 2) Is violet less than green (y/n)? n 3) Is red less than green (y/n)? n 4) Is red less than indigo (y/n)? n 5) Is green less than indigo (y/n)? y 6) Is red less than blue (y/n)? n 7) Is indigo less than blue (y/n)? n 8) Is green less than blue (y/n)? n 9) Is indigo less than yellow (y/n)? y 10) Is violet less than yellow (y/n)? y 11) Is red less than orange (y/n)? n 12) Is green less than orange (y/n)? y 13) Is indigo less than orange (y/n)? y Sorted list: blue, green, indigo, orange, red, violet, yellow</pre> =={{header\|OCaml}}== Standard sort with custom comparator List: <syntaxhighlight lang="ocaml">let () = let count = ref 0 in let mycmp s1 s2 = ( incr count; Printf.printf "(%d) Is %s <, ==, or > %s? Answer -1, 0, or 1: " (!count) s1 s2; read_int () ) in let items = ["violet"; "red"; "green"; "indigo"; "blue"; "yellow"; "orange"] in let sorted = List.sort mycmp items in List.iter (Printf.printf "%s ") sorted; print_newline ()</syntaxhighlight> {{out}} <pre> (1) Is violet <, ==, or > red? Answer -1, 0, or 1: 1 (2) Is red <, ==, or > green? Answer -1, 0, or 1: -1 (3) Is violet <, ==, or > green? Answer -1, 0, or 1: 1 (4) Is indigo <, ==, or > blue? Answer -1, 0, or 1: 1 (5) Is yellow <, ==, or > orange? Answer -1, 0, or 1: 1 (6) Is blue <, ==, or > orange? Answer -1, 0, or 1: 1 (7) Is blue <, ==, or > yellow? Answer -1, 0, or 1: 1 (8) Is violet <, ==, or > indigo? Answer -1, 0, or 1: 1 (9) Is green <, ==, or > indigo? Answer -1, 0, or 1: -1 (10) Is green <, ==, or > blue? Answer -1, 0, or 1: -1 (11) Is green <, ==, or > yellow? Answer -1, 0, or 1: 1 (12) Is red <, ==, or > yellow? Answer -1, 0, or 1: -1 (13) Is red <, ==, or > orange? Answer -1, 0, or 1: -1 red orange yellow green blue indigo violet </pre> Array: <syntaxhighlight lang="ocaml">let () = let count = ref 0 in let mycmp s1 s2 = ( incr count; Printf.printf "(%d) Is %s <, ==, or > %s? Answer -1, 0, or 1: " (!count) s1 s2; read_int () ) in let items = [\|"violet"; "red"; "green"; "indigo"; "blue"; "yellow"; "orange"\|] in Array.sort mycmp items; Array.iter (Printf.printf "%s ") items; print_newline ()</syntaxhighlight> {{out}} <pre> (1) Is blue <, ==, or > yellow? Answer -1, 0, or 1: 1 (2) Is blue <, ==, or > orange? Answer -1, 0, or 1: 1 (3) Is blue <, ==, or > red? Answer -1, 0, or 1: 1 (4) Is blue <, ==, or > green? Answer -1, 0, or 1: 1 (5) Is blue <, ==, or > indigo? Answer -1, 0, or 1: -1 (6) Is indigo <, ==, or > violet? Answer -1, 0, or 1: -1 (7) Is blue <, ==, or > green? Answer -1, 0, or 1: 1 (8) Is blue <, ==, or > indigo? Answer -1, 0, or 1: -1 (9) Is indigo <, ==, or > orange? Answer -1, 0, or 1: 1 (10) Is blue <, ==, or > green? Answer -1, 0, or 1: 1 (11) Is blue <, ==, or > orange? Answer -1, 0, or 1: 1 (12) Is red <, ==, or > yellow? Answer -1, 0, or 1: -1 (13) Is blue <, ==, or > yellow? Answer -1, 0, or 1: 1 (14) Is yellow <, ==, or > green? Answer -1, 0, or 1: -1 (15) Is green <, ==, or > orange? Answer -1, 0, or 1: 1 (16) Is green <, ==, or > red? Answer -1, 0, or 1: 1 (17) Is yellow <, ==, or > red? Answer -1, 0, or 1: 1 (18) Is yellow <, ==, or > orange? Answer -1, 0, or 1: 1 (19) Is orange <, ==, or > red? Answer -1, 0, or 1: 1 red orange yellow green blue indigo violet </pre> =={{header\|Perl}}== <~~lang~~syntaxhighlight lang="perl">#!/usr/bin/perl use strict; # https://rosettacode.org/wiki/Order_by_pair_comparisons Line 216 ⟶ 1,397: my @sorted = sort ask qw( violet red green indigo blue yellow orange ); print "sorted: @sorted\n";</~~lang~~syntaxhighlight> {{out}} <pre> Line 241 ⟶ 1,422: I picked an initial ordering that requires a fairly easy to remember set of answers: 4Y then alternate.<br> The builtin sort(s) use an initial gap of 10%, ultimately balancing #comparisons against cache hits, which leads to a wider range of #questions, as said best case 6, worst case 21. A better match to the narrower range of Python (I think 10..14) could probably be made using a copy of custom_sort (it is only 52 lines) with an initial 50% gap. <!--<~~lang~~syntaxhighlight ~~Phix~~lang="phix">(notonline)--> <span style="color: #004080;">integer</span> <span style="color: #000000;">qn</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span> <span style="color: #008080;">function</span> <span style="color: #000000;">ask</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> Line 252 ⟶ 1,433: <span style="color: #0000FF;">?</span><span style="color: #7060A8;">custom_sort</span><span style="color: #0000FF;">(</span><span style="color: #000000;">ask</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">split</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"violet orange red yellow green blue indigo"</span><span style="color: #0000FF;">))</span> <!--</~~lang~~syntaxhighlight>--> {{out}} <pre> Line 273 ⟶ 1,454: Uses binary search to insert successive items into a growing ordered list. Comparisons are asked for. <~~lang~~syntaxhighlight lang="python">def _insort_right(a, x, q): """ Insert item x in list a, and keep it sorted assuming a is sorted. Line 298 ⟶ 1,479: items = 'violet red green indigo blue yellow orange'.split() ans, questions = order(items) print('\n' + ' '.join(ans))</~~lang~~syntaxhighlight> {{out}} Line 332 ⟶ 1,513: This uses a custom comparator together with [https://docs.python.org/3/library/functools.html?highlight=cmp_to_key#functools.cmp_to_key functools.cmp_to_key] to sort the previous order in fourteen questions. <~~lang~~syntaxhighlight lang="python">from functools import cmp_to_key def user_cmp(a, b): Line 340 ⟶ 1,521: items = 'violet red green indigo blue yellow orange'.split() ans = sorted(items, key=cmp_to_key(user_cmp)) print('\n' + ' '.join(ans))</~~lang~~syntaxhighlight> {{out}} Line 372 ⟶ 1,553: red orange yellow green blue indigo violet</pre> =={{header\|Quackery}}== <code>sortwith</code> sorts by insertion sort by default, of by merge sort falling back to insertion sort for nests of fewer than 16 items if the Quackery extensions are loaded. In either instance, as this is sorting a nest of seven items, it will be by insertion sort. <syntaxhighlight lang="quackery"> [ $ "Is " swap join $ " before " join swap join $ "? (y/n) " join input $ "y" = ] is askuser $ "red orange yellow green blue indigo violet" say "Correct order --> " dup echo$ cr cr nest$ shuffle dup witheach [ echo$ sp ] cr cr sortwith askuser cr witheach [ echo$ sp ] cr</syntaxhighlight> {{out}} <pre>Correct order --> red orange yellow green blue indigo violet green blue orange indigo yellow violet red Is blue before green? (y/n) n Is orange before green? (y/n) y Is indigo before orange? (y/n) n Is indigo before green? (y/n) n Is indigo before blue? (y/n) n Is yellow before orange? (y/n) n Is yellow before green? (y/n) y Is violet before orange? (y/n) n Is violet before yellow? (y/n) n Is violet before green? (y/n) n Is violet before blue? (y/n) n Is violet before indigo? (y/n) n Is red before orange? (y/n) y red orange yellow green blue indigo violet </pre> =={{header\|Raku}}== Line 377 ⟶ 1,599: Since the calls to the comparator are minimized, and the info that the user provides is analogous to the required return values of the comparator, we just need to embed the prompt directly in the comparator. <syntaxhighlight lang="raku" ~~perl6~~line>my $ask_count = 0; sub by_asking ( $a, $b ) { $ask_count++; Line 398 ⟶ 1,620: die if @sorted».substr(0,1).join ne 'roygbiv'; my $expected_ask_count = @colors.elems log(@colors.elems); warn "Too many questions? ({:$ask_count} > {:$expected_ask_count})" if $ask_count > $expected_ask_count;</~~lang~~syntaxhighlight> {{out}} <pre> Line 423 ⟶ 1,645: Also note that lists in REXX start with unity, not zero. <syntaxhighlight lang="rexx">/REXX pgm orders some items based on (correct) answers from a carbon─based life form. / colors= 'violet red green indigo blue yellow orange' q= 0; #= 0; $= Line 447 ⟶ 1,669: else lo= mid + 1 end /q/ $= subword($, 1, lo) x subword($, lo+1); return q</~~lang~~syntaxhighlight> {{out\|output\|text=  (only showing the results and eliding the querying/answering):}} <pre> Line 465 ⟶ 1,687: final ordering: red orange yellow green blue indigo violet </pre> =={{header\|Ruby}}== ===Ruby: Binary search insertion sort=== <syntaxhighlight lang="ruby">items = ["violet", "red", "green", "indigo", "blue", "yellow", "orange"] count = 0 sortedItems = [] items.each {\|item\| puts "Inserting '#{item}' into #{sortedItems}" spotToInsert = sortedItems.bsearch_index{\|x\| count += 1 print "(#{count}) Is #{item} < #{x}? " gets.start_with?('y') } \|\| sortedItems.length # if insertion point is at the end, bsearch_index returns nil sortedItems.insert(spotToInsert, item) } p sortedItems</syntaxhighlight> {{out}} <pre> Inserting 'violet' into [] Inserting 'red' into ["violet"] (1) Is red < violet? y Inserting 'green' into ["red", "violet"] (2) Is green < violet? y (3) Is green < red? n Inserting 'indigo' into ["red", "green", "violet"] (4) Is indigo < green? n (5) Is indigo < violet? y Inserting 'blue' into ["red", "green", "indigo", "violet"] (6) Is blue < indigo? y (7) Is blue < green? n Inserting 'yellow' into ["red", "green", "blue", "indigo", "violet"] (8) Is yellow < blue? y (9) Is yellow < green? y (10) Is yellow < red? n Inserting 'orange' into ["red", "yellow", "green", "blue", "indigo", "violet"] (11) Is orange < blue? y (12) Is orange < yellow? y (13) Is orange < red? n ["red", "orange", "yellow", "green", "blue", "indigo", "violet"] </pre> ===Ruby: Standard sort with custom comparator=== <syntaxhighlight lang="ruby">items = ["violet", "red", "green", "indigo", "blue", "yellow", "orange"] count = 0 p items.sort {\|a, b\| count += 1 print "(#{count}) Is #{a} <, =, or > #{b}. Answer -1, 0, or 1: " gets.to_i }</syntaxhighlight> {{out}} <pre> (1) Is violet <, =, or > red. Answer -1, 0, or 1: 1 (2) Is violet <, =, or > green. Answer -1, 0, or 1: 1 (3) Is red <, =, or > green. Answer -1, 0, or 1: -1 (4) Is violet <, =, or > indigo. Answer -1, 0, or 1: 1 (5) Is green <, =, or > indigo. Answer -1, 0, or 1: -1 (6) Is violet <, =, or > blue. Answer -1, 0, or 1: 1 (7) Is indigo <, =, or > blue. Answer -1, 0, or 1: 1 (8) Is green <, =, or > blue. Answer -1, 0, or 1: -1 (9) Is violet <, =, or > yellow. Answer -1, 0, or 1: 1 (10) Is indigo <, =, or > yellow. Answer -1, 0, or 1: 1 (11) Is blue <, =, or > yellow. Answer -1, 0, or 1: 1 (12) Is green <, =, or > yellow. Answer -1, 0, or 1: 1 (13) Is red <, =, or > yellow. Answer -1, 0, or 1: -1 (14) Is violet <, =, or > orange. Answer -1, 0, or 1: 1 (15) Is indigo <, =, or > orange. Answer -1, 0, or 1: 1 (16) Is blue <, =, or > orange. Answer -1, 0, or 1: 1 (17) Is green <, =, or > orange. Answer -1, 0, or 1: 1 (18) Is yellow <, =, or > orange. Answer -1, 0, or 1: 1 (19) Is red <, =, or > orange. Answer -1, 0, or 1: -1 ["red", "orange", "yellow", "green", "blue", "indigo", "violet"] </pre> Line 471 ⟶ 1,765: {{libheader\|Wren-ioutil}} {{libheader\|Wren-fmt}} <~~lang~~syntaxhighlight ~~ecmascript~~lang="wren">import "./ioutil" for Input import "./fmt" for Fmt // Inserts item x in list a, and keeps it sorted assuming a is already sorted. Line 506 ⟶ 1,800: var ordered = order.call(items) System.print("\nThe colors of the rainbow, in sorted order, are:") System.print(ordered)</~~lang~~syntaxhighlight> {{out}} Line 526 ⟶ 1,820: The colors of the rainbow, in sorted order, are: [red, orange, yellow, green, blue, indigo, violet] </pre> =={{header\|XPL0}}== <syntaxhighlight lang "XPL0">include xpllib; \for Print int Items, Size, I, J, Gap, JG, T, C, Count; [Items:= ["violet", "red", "green", "indigo", "blue", "yellow", "orange"]; Size:= 7; Count:= 0; Gap:= Size>>1; while Gap > 0 do [for I:= Gap to Size-1 do [J:= I - Gap; loop [JG:= J + Gap; Count:= Count+1; Print("%2d: Is %6s less than %6s (y/n)? ", Count, Items(J), Items(JG)); repeat OpenI(1); C:= ChIn(1); until C=^y or C=^n; ChOut(0, C); CrLf(0); if C = ^y then quit; T:= Items(J); Items(J):= Items(JG); Items(JG):= T; J:= J - Gap; if J < 0 then quit; ]; ]; Gap:= Gap>>1; ]; Print("The colors of the rainbow, in sorted order, are:\n"); for I:= 0 to Size-2 do Print("%s, ", Items(I)); Print("%s\n", Items(I)); ]</syntaxhighlight> {{out}} <pre> 1: Is violet less than indigo (y/n)? n 2: Is red less than blue (y/n)? y 3: Is green less than yellow (y/n)? n 4: Is violet less than orange (y/n)? n 5: Is indigo less than orange (y/n)? n 6: Is orange less than red (y/n)? n 7: Is orange less than yellow (y/n)? y 8: Is yellow less than indigo (y/n)? y 9: Is indigo less than blue (y/n)? n 10: Is yellow less than blue (y/n)? y 11: Is indigo less than green (y/n)? n 12: Is blue less than green (y/n)? n 13: Is yellow less than green (y/n)? y 14: Is indigo less than violet (y/n)? y The colors of the rainbow, in sorted order, are: red, orange, yellow, green, blue, indigo, violet </pre>