Print 123454321 without if statements and using only 2 variables [closed]

Question

The challenge: Write a function, that delivers following output: "1 2 3 4 5 4 3 2 1".

Kids stuff? Of course. But here's the point:

• You only can use: 1 for loop, 2 int variables.

• You must not use: IF terms, another function, ...

• Do not hardcode the output

There are also some more restrictions to make this harder:

• No functions like abs or sth. else are allowed! (Yep, it's possible)
• No static output like echo "1 2 3 4 5 4 3 2 1"

This is a popularity-contest, so the answer with the most votes wins!

Answer 1

Python

One for loop, one int variable (i), no if, no other functions (unless you consider print or +-*/ as functions, haha):

for i in range(9):
    print i+1 - 2*(i//5)*(i-4),

Answer 2

C

No function, no hidden IF (abs, min, etc.)

#include <stdio.h>

int main() 
{
int sum=0;
for (int i=3; i<12; i++)
    {
    sum += 1-2*(i/8);
    printf("%d\n", sum );
    }
}

Explanation : The 4th bit of i is the heart of the trick : it's 0 for [3,7] and 1 for [8,11].

i/8 gives the value of the bit (just like i>>3) for i in [3,11] it gives : 0, 0, 0, 0, 0, 1, 1, 1, 1

1-2*(i/8) is simple math to obtain 1, 1, 1, 1, 1, -1, -1, -1, -1

+= is used to sum the values

Answer 3

Javascript, 32 characters

+new Date(1970,0,2,11,17,34,321)

edit: not timezone-dependant, 42 chars

+new Date(Date.UTC(1970,0,2,10,17,34,321))

Answer 4

Cobra

Really, this is quite trivial.

class Program
    def main
        for i in 10, Console.write(5 - Math.abs(5 - i))

Or

class Program
    def main
        v as int = 123454321
        for i in v.toString, Console.write(i)

Or even simpler

class Program
    def main
        print 1, 2, 3, 4, 5, 4, 3, 2, 1

But if you insist on following the question exactly:

class Program
    def main
        num as int = 123454321
        for i in '[num]'
            Console.write(i)
            Console.write(' ')

This uses only one integer variable, only one loop, and the only function explicitly called is used for output.

Answer 5

Golfscript, 16 characters

6,(;)1$-1%++' '*

I assume this is meant to be a code golf?

No variables. All data (two arrays and a number) is on the stack. The only loops are implicit ones.

Online demonstration: http://golfscript.apphb.com/?c=NiwoOykxJC0xJSsrJyAnKg%3D%3D

Answer 6

C++: Works finely in VC 11.0

#include <iostream>
#include <cstring>
#include <vector>
#include <conio.h>
#include <algorithm>

using namespace std;

bool called = false;
int main();
int f() {
    called = true;
    typedef vector<int>::iterator _v_interate;
    int l;
    static bool d;
    vector<int> iVector;
    for(l = 1; (true); (!d) ? l++ : l--) {
        _v_interate i = find(iVector.begin(), iVector.end(), 4);
        _v_interate i2 = find(iVector.begin(), iVector.end(), 3);
        _v_interate i3 = find(iVector.begin(), iVector.end(), 2);
        _v_interate i4 = find(iVector.begin(), iVector.end(), 1);
        _v_interate i5 = find(iVector.begin(), iVector.end(), 5);
        d =  (i != iVector.end()) &&  (i2 != iVector.end()) &&  (i3 != iVector.end()) &&  (i4 != iVector.end()) ? 1 : 0;
        iVector.push_back(l);
        cout << l << " ";
        (d && (l==1) ? main() : 0);
    }
    return 0;
}

int main() {
    !called ? f() : 0;
    _getch();
    exit(0); // Removing the exit(0) causes an infinite loop; I don't know why.
    return 0;
}

A simple solution:

#include <iostream>

void main() {
  cout << "1 2 3 4 5 4 3 2 1";
}

Answer 7

Delphi XE3

I dont think this requires much explaining right?

function p:string;
var
  i:integer;
begin
  for I:=1 to 4 do
    Result:=Format('%s%d ',[Result,I]);
  Result:=Format('%s%d%s',[Result,5,ReverseString(Result)]);
end;

In case it does. Function loops from 1 to 4, and keeps adding the number + [space].
Then it adds I again which became 5 which made it quit the loop and adds the reversed string as it is now.

Variation

function p:string;

const s='123454321' var i:integer; begin s:='123454321'; for I:=1to Length(s) do Result:=Format('%s %s',[Result,s[i]]); Exit(Trim(Result));
end; This might seem hardcoded but the constant doesnt have the spaces that are required.
Although it might seem impossible but there is a solution that is even lamer than this.

function p:string;
const
  s='123454321'
begin
  result:=Format('%s %s %s %s %s %s %s %s %s',[s[1],s[2],s[3],s[4],s[5],s[6],s[7],s[8],s[9]])  
  {or}  
  result:=Format('%s %s %s %s %s %s %s %s %s',[s[1],s[2],s[3],s[4],s[5],s[4],s[3],s[2],s[1]])
 {OR!}  
  result:=Format('%d %d %d %d %d %d %d %d %d',[1,2,3,4,5,4,3,2,1])
end;

Answer 8

Perl

Version 1:

for(1..9){
    $x = ($_%18 - 5);
    print 5 - ($x, -$x)[$x < -$x] . " ";
}

Version 2:

for(1..9){
    $x = ($_%18 - 5);
    $x =~ s/-//;
    print 5 - $x . " ";
}

For both versions: 1 For loop, and 2 variables, $_ and $x, and I'm not using if or any other function.

Answer 9

Ruby - 47 chars

(1..4).to_a.push((1..5).to_a.reverse).join ' '

Edit - 33 chars

[*(1..4),[*(1..5)].reverse]*' '

Answer 10

Java

Used one loop and the loop variable. Added a constant for the upper bound.

public class Test {
   private static final int BOUND = 5;
   public static void main(String[] args) {
      for (int i = 1; i < BOUND * 2; i++) {
         System.out.print(i - (2 * ((i % BOUND) * (i / BOUND))) + " ");
      }
   }
}

Answer 11

Brainfuck, 83

+++++++[>+++++++>+++++++>+++++++>+++++++>+++++++<<<<<-]>.>+.>++.>+++.>++++.<.<.<.<.

Only 1 loop, no ifs (if you don't count the loop as an if). No int variables.

Answer 12

JavaScript

function f(){
  for ( var i=1,j=5; j>0; ++i>j&&(--i,--i,--j) )
    console.log(i);
}

Answer 13

C

Not sure if it follows exactly the rules but my answer is below

int main()
{
    int x;
    for(x = 123454321; x > 10; x /= 10)
    {
        printf("%d ", x % 10);
    }
    printf("%d", x);
    return 0;
}

Run the code

Answer 14

Well, I guess the fastest and most naive solution (in Python) would be:

' '.join (str(x) for x in range(1,6)) + ' ' + ' '.join (str(x) for x in range(4,0,-1))

Answer 15

Javascript

This might not be the best and fastest way to do it, but I like what I came up with.

z = '';
for (x = 1; x <= 5; x++) { // Don't need a loop, but hey, I like loops!
    z += x + ' '; // Creates "1 2 3 4 5 "
}
document.getElementById('result').innerHTML = z + z.split("").reverse().join("").substring(2, 10); 
// "1 2 3 4 5 " + " 4 3 2 1"

Result:

1 2 3 4 5 4 3 2 1

You can see it in action Here!

Answer 16

As 2.0

var num:Int = 11111;
alert(num*num);

Answer 17

Java, 79 chars (standalone: 131 chars)

int b=-1,i=1;for(;i>0&(i<5||(b=1)==1);i-=b){System.out.print(i+(b==i?"":" "));}

Uses two ints, and no other variables. No if statements, just a for loop for evaluation. This will run on its own when put in the main(String[] args) method in a class, or in any other function. The full code, including class declaration and method, is 131 chars.

public class M{public static void main(String[]a){int b=-1,i=1;for(;i>0&(i<5||(b=1)==1);i-=b){System.out.print(i+(b==i?"":" "));}}}

While I'm at it:

PHP, 70 chars (standalone: 78 chars)

$b=-1;for($i=1;$i>0&($i<5||($b=1)==1);$i-=$b){echo$i.($b==$i?"":" ");}

Uses same method as Java. Standalone script is 62 chars:

<?php $b=-1;for($i=1;$i>0&($i<5||($b=1)==1);$i-=$b){echo$i.($b==$i?"":" ");}?>

Answer 18

C

#include <stdio.h>

int main(void) {
    int i;
    for (i = 21911761; i > 0 && printf("%d", i&7); i = i>>3)
        i > 1 && printf(" ");

    return 0;
}

Answer 19

Fortran 90: 60

integer::j(9)=5;do i=1,4;j(i)=i;j(10-i)=i;enddo;print*,j;end

If you wanted it formatted slightly better, I can add a few characters to make the print statement print'(9i2)',j. Ungolfed & written properly, this is

program main
   implicit none
   integer :: i, j(9)
   j = 5
   do i=1,4
      j(i) = i
      j(10-i) = i
   enddo
   print *,j
end program main

Answer 20

Powershell

((1..9)|%{
    $_ = ($_%18-5)
5 - @($_,-$_)[$_ -lt -$_]
})-join ' '

1 variable, no if, no functions (unless you were to count -join which is just for displaying the data...

Explanation: Loops from 1 to 9, then for each value calculates the reminder of the current value by 18, then subtracts 5 and assigns it to the currently used $_ variable. After that it evaluates $_ < -$_ (this is to handle negative values), and uses the result (False/True) to get the value from the array @($_,-$_), therefore making sure we always get a positive number in this case, after that it subtracts this number to 5 and finally joins the results with space.

Answer 21

Scala, 53

(4 to 12).foldLeft(1)((a,b)=>{print(a);a+1-2*(b/8)})

I stole the neat bit shifting idea from @cpri

http://scalafiddle.net/console/3b3fff6463464959dcd1b68d0320f781