Stern-Brocot sequence: Difference between revisions

=={{header|PureBasic}}==

<lang PureBasic>EnableExplicit

Define.i i

If OpenConsole("")

PrintN("Stern-Brocot_sequence")

Else

End 1

EndIf

Procedure.i f(n.i)

If n<2

ProcedureReturn n

ElseIf n&1

ProcedureReturn f(n/2)+f(n/2+1)

Else

ProcedureReturn f(n/2)

EndIf

EndProcedure

Procedure.i gcd(a.i,b.i)

If b : ProcedureReturn gcd(b,a%b) : EndIf

ProcedureReturn a

EndProcedure

Procedure.i ind(m.i)

Define.i i=1

While f(i)<>m : i+1 : Wend

ProcedureReturn i

EndProcedure

Print("First 15 elements: ")

For i=1 To 15

Print(Str(f(i))+Space(3))

Next

PrintN(~"\n")

For i=1 To 10

PrintN(RSet(Str(i),3)+" is at pos. #"+Str(ind(i)))

Next

PrintN("100 is at pos. #"+Str(ind(100)))

PrintN("")

i=1

While i<1000 And gcd(f(i),f(i+1))=1 : i+1 : Wend

If i=1000

PrintN("All GCDs are 1.")

Else

PrintN("GCD of "+Str(i)+" and "+Str(i+1)+" is not 1")

EndIf

Input()</lang>

{{out}}

<pre>Stern-Brocot_sequence

First 15 elements: 1 1 2 1 3 2 3 1 4 3 5 2 5 3 4

1 is at pos. #1

2 is at pos. #3

3 is at pos. #5

4 is at pos. #9

5 is at pos. #11

6 is at pos. #33

7 is at pos. #19

8 is at pos. #21

9 is at pos. #35

10 is at pos. #39

100 is at pos. #1179

All GCDs are 1.</pre>