Code Golf Christmas Edition: How to print out a Christmas tree of height N

Question

Given a number N, how can I print out a Christmas tree of height N using the least number of code characters? N is assumed constrained to a min val of 3, and a max val of 30 (bounds and error checking are not necessary). N is given as the one and only command line argument to your program or script.

All languages appreciated, if you see a language already implemented and you can make it shorter, edit if possible - comment otherwise and hope someone cleans up the mess. Include newlines and whitespace for clarity, but don't include them in the character count.

A Christmas tree is generated as such, with its "trunk" consisting of only a centered "*"

N = 3:

   *
  ***
 *****
   *

N = 4:

    *
   ***
  *****
 *******
    *

N = 5:

     *
    ***
   *****
  *******
 *********
     *

N defines the height of the branches not including the one line trunk.

Merry Christmas SO!

Answer 1

Language: Perl, Char count: 50 (1 relevant spaces)

perl: one line version:

print$"x($a-$_),'*'x($_*2+1),$/for 0..($a=pop)-1,0

and now with more whitesapce:

print $"  x ( $a - $_ ),             #"# Syntax Highlight Hacking Comment
      '*' x ( $_ * 2  + 1),
      $/
for 0 .. ( $a = pop ) - 1, 0;

$ perl tree.pl 3
   *
  ***
 *****
   *
$ perl tree.pl 11
           *
          ***
         *****
        *******
       *********
      ***********
     *************
    ***************
   *****************
  *******************
 *********************
           *
$

Expanded Explanation for Non-Perl Users.

# print $Default_List_Seperator ( a space )  
#     repeated ( $a - $currentloopiterationvalue ) times,
print $" x ( $a - $_ ), 
#"# print '*' repeated( $currentloopiteration * 2 + 1 ) times. 
  '*' x ( $_ * 2  + 1),
# print $Default_input_record_seperator ( a newline )
  $/
# repeat the above code, in a loop, 
#   iterating values 0 to ( n - 1) , and then doing 0 again
for 0 .. ( $a = pop ) - 1, 0;
# prior to loop iteration, set n to the first item popped off the default list, 
#   which in this context is the parameters passed on the command line.

Answer 2

Language: Brainfuck, Char count: 240

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

Not yet done. It works, but only with single-digit numbers.

EDIT: Done! Works for interpreters using 0 as EOF. See NOTEs in commented source for those with -1.

EDIT again: I should note that because Brainfuck lacks a standard method for reading command line arguments, I used stdin (standard input) instead. ASCII, of course.

EDIT a third time: Oh dear, it seems I stripped . (output) characters when condensing the code. Fixed...

Here's the basic memory management of the main loop. I'm sure it can be heavily optimized to reduce the character count by 30 or so.

1. Temporary
2. Copy of counter
3. Counter (counts to 0)
4. Space character (decimal 32)
5. Asterisk character (decimal 42)
6. Number of asterisks on current line (1 + 2*counter)
7. Temporary
8. New line character
9. Temporary?
10. Total number of lines (i.e. input value; stored until the very end, when printing the trunk)

Condensed version:

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

And the pretty version:

ASCII to number
,>
++++++++[-<------>]  = 48 ('0')

Second digit (may be NULL)
,
NOTE:   Add plus sign here if your interpreter uses negative one for EOF
[ NOTE: Then add minus sign here
 >++++++++[-<------>]
 <<[->++++++++++<]>>  Add first digit by tens
]

Duplicate number
<[->+>+>>>>>>>+<<<<<<<<<]>>

Space char
>>++++++++[-<++++>]

Asterisk char
>++++++[-<+++++++>]

Star count
+

New line char
>>>++[-<+++++>]<<<

<<<

Main loop
[
Print leading spaces
-[>.<-]

Undo delete
<[-<+>>+<]
<[->+<]
>>

Print stars
>>>[-<.>>+<]

Add stars and print new line
>[-<+>]
>.<
<++

<<<

-<->
End main loop
]

Print the trunk
>>>>>>>
-[-<<<<<<.>>>>>>]
<<<<<.

Merry Christmas =)

Answer 3

J

24 characters.

(,{.)(}:@|."1,.])[\'*'$~

   (,{.)(}:@|."1,.])[\'*'$~5
    *    
   ***   
  *****  
 ******* 
*********
    *    

Explanation:

'*'$~5
*****

[\'*'$~5
*    
**   
***  
**** 
*****

Then }:@|."1 reverses each row and strips off the last column, and ,. staples it to ].

Then ,{. pastes the first column onto the bottom.

Previous entries:

29 characters, no spaces at all.

   ((\:i.@#),}.)"1$&'*'"0>:0,~i.3
  *
 ***
*****
  *
   ((\:i.@#),}.)"1$&'*'"0>:0,~i.11
          *
         ***
        *****
       *******
      *********
     ***********
    *************
   ***************
  *****************
 *******************
*********************
          *

---

   NB. count from 1 to n, then 1 again
   >:0,~i.3
1 2 3 1
   NB. replicate '*' x times each
   $&'*'"0>:0,~i.3
*
**
***
*
   NB. reverse each row
   (\:i.@#)"1$&'*'"0>:0,~i.3
  *
 **
***
  *
   NB. strip off leading column
   }."1$&'*'"0>:0,~i.3

*
**

   NB. paste together
   ((\:i.@#),}.)"1$&'*'"0>:0,~i.3
  *
 ***
*****
  *

Answer 4

Language: Python (through shell), Char count: 64 (2 significant spaces)

python -c "
n=w=$1
s=1
while w:
    print' '*w+'*'*s
    s+=2
    w-=1
print' '*n+'*'"

$ sh ax6 11
           *
          ***
         *****
        *******
       *********
      ***********
     *************
    ***************
   *****************
  *******************
 *********************
           *

Answer 5

Language: Windows Batch Script (shocking!)

@echo off
echo Enable delayed environment variable expansion with CMD.EXE /V

rem Branches
for /l %%k in (1,1,%1) do (
set /a A=%1 - %%k
set /a B=2 * %%k - 1
set AA=
for /l %%i in (1,1,!A!) do set "AA=!AA! "
set BB=
for /l %%i in (1,1,!B!) do set BB=*!BB!
echo !AA!!BB!
)

rem Trunk
set /a A=%1 - 1
set AA=
for /l %%i in (1,1,!A!) do set "AA=!AA! "
echo !AA!*

Answer 6

Language: Ruby, Char count: 64

n=ARGV[0].to_i
((1..n).to_a+[1]).each{|i|puts' '*(n-i)+'*'*(2*i-1)}

n=$*[0].to_i
((1..n).to_a<<1).each{|i|puts' '*(n-i)+'*'*(2*i-1)}

Merry Christmas all!

Edit: Improvements added as suggested by Joshua Swink

Answer 7

Language: x86 asm 16-bit, Byte count: 50

No assembly version yet? :)

	bits 16
	org 100h

	mov si, 82h
	lodsb
	aaa
	mov cx, ax
	mov dx, 1
	push cx 
	mov al, 20h
	int 29h
	loop $-2
	push dx
	mov al, 2ah
	int 29h
	dec dx
	jnz $-3
	pop dx
	mov al, 0ah
	int 29h
	inc dx
	inc dx
	pop cx
	loop $-23
	shr dx, 1
	xchg cx, dx
	mov al, 20h
	int 29h
	loop $-2
	mov al, 2ah
	int 29h
	ret

(Note: N is limited to 1 - 9 in this version)

G:\>tree 9
         *
        ***
       *****
      *******
     *********
    ***********
   *************
  ***************
 *****************
         *

Download here

Answer 8

Language: C#, Char count: 120

static void Main(string[] a)
{
    int h = int.Parse(a[0]);

    for (int n = 1; n < h + 2; n++)
        Console.WriteLine(n <= h ?
            new String('*', n * 2 - 1).PadLeft(h + n) :
            "*".PadLeft(h + 1));
    }
}

Just the code, without formatting (120 characters):

int h=int.Parse(a[0]);for(int n=1;n<h+2;n++)Console.WriteLine(n<=h?new String('*',n*2-1).PadLeft(h+n):"*".PadLeft(h+1));

Version with 109 characters (just the code):

for(int i=1,n=int.Parse(a[0]);i<n+2;i++)Console.WriteLine(new String('*',(i*2-1)%(n*2)).PadLeft((n+(i-1)%n)));

Result for height = 10:

          *
         ***
        *****
       *******
      *********
     ***********
    *************
   ***************
  *****************
 *******************
          *

Answer 9

python, "-c" trick... @61 chars (and one line)

python -c"for i in range($1)+[0]:print' '*($1-i)+'*'*(2*i+1)"

Answer 10

Language: dc (through shell) Char count: 83

A little bit shorter dc version:

dc -e '?d1rdsv[d32r[[rdPr1-d0<a]dsaxszsz]dsbx1-rd42rlbx2+r10Plv1-dsv0<c]dscxszsz32rlbx[*]p' <<<$1

EDIT: changed constant 10 into $1

Answer 11

Here's a reasonably space-efficient Haskell version, at 107 characters:

main=interact$(\g->unlines$map(\a->replicate(g-a)' '++replicate(a*2-1)'*')$[1..g]++[1]).(read::[Char]->Int)

running it:

$ echo 6 | runhaskell tree.hs
     *
    ***
   *****
  *******
 *********
***********
     *

Merry Christmas, all :)

Answer 12

Language: dc (through shell), Char count: 119 (1 significant space)

Just for the obscurity of it :)

dc -e "$1dsnsm"'
[[ ]n]ss
[[*]n]st
[[
]n]sl
[s2s1[l2xl11-ds10<T]dsTx]sR
[lndlslRxlcdltlRxllx2+sc1-dsn0<M]sM
1sclMxlmlslRxltxllx
'

$ sh ax3 10
          *
         ***
        *****
       *******
      *********
     ***********
    *************
   ***************
  *****************
 *******************
          *

Answer 13

Ridiculously long C++ one:

#include <iostream>
#include <conio.h>

using namespace std;

class CTree
{
// Members
private:
    unsigned short m_Lvl;
    unsigned short m_Spc;

// Construction
public:
    CTree(unsigned short lvl)
        : m_Lvl(lvl), m_Spc(0) {}
private:
    CTree(unsigned short lvl, unsigned short spc)
        : m_Lvl(lvl), m_Spc(spc) {}

// Operations
public:
    void Print()
    {
        // Print the leaves.
        if (m_Lvl)
        {
            CTree(m_Lvl-1 , m_Spc+1).Print();
            Line();
        }

        // Print the trunk.
        if (!m_Spc)
            CTree(1 , m_Lvl ? (m_Lvl - 1) : 0).Line();
    }
private:
    void Line()
    {
        // Indent the current line.
        for (unsigned short s = m_Spc; s--; )
            cout << ' ';

        // Print the leaves.
        for (unsigned short l = m_Lvl; --l; )
            cout << '*' << '*';
        cout << '*' << endl;
    }
};

int main(int argc, char** argv)
{
    // Validate the command line.
    if ((argc != 2) || !isdigit(argv[1][0]))
    {
        cout << "Command line: tree.exe number_of_lines";
        _getch();
        exit(1);
    }

    // Validate the number of lines.
    short lvl = (short)atoi(argv[1]);
    if (lvl < 0)
    {
        cout << "Do you really think " << lvl << " lines can be printed?";
        _getch();
        exit(1);
    }
    if (lvl > 40)
    {
        cout << "Sorry, but a " << lvl << "-line tree is too big to be printed.";
        _getch();
        exit(1);
    }

    // Print the tree.
    CTree((unsigned short)lvl).Print();

    // The user must press a key before the program finishes.
    _getch();
    return 0;
}

---

EDIT: I must add that this program doesn't follow the specifications exactly. When the input argument is N, it prints a (N+1)-line tree.

Merry X-Mas to the SO community

---

EDIT: Debugged the program and corrected some nasty errors.

Answer 14

Better C++, around 210 chars:

#include <iostream>
using namespace std;
ostream& ChristmasTree(ostream& os, int height) {
    for (int i = 1; i <= height; ++i) {
        os << string(height-i, ' ') << string(2*i-1, '*') << endl;
    }
    os << string(height-1, ' ') << '*' << endl;
    return os;
}

Minimized to 179:

#include <iostream>
using namespace std;ostream& xmas(ostream&o,int h){for(int i=1;i<=h;++i){o<<string(h-i,' ')<<string(2*i-1,'*')<<endl;}o<<string(h-1,' ')<<'*'<<endl;return o;}

Answer 15

Improving ΤΖΩΤΖΙΟΥ's answer. I can't comment, so here is a new post. 72 characters.

import sys
n=int(sys.argv[1])
for i in range(n)+[0]:
   print ("*"*(2*i+1)).center(2*n)

Using the "python -c" trick, 61 characters.

python -c "
for i in range($1)+[0]:
   print ('*'*(2*i+1)).center(2*$1)
"

I learned the center function and that "python -c" can accept more than one line code. Thanks, ΤΖΩΤΖΙΟΥ.

Answer 16

C# using Linq:

    using System;
    using System.Linq;
    class Program
        {
            static void Main(string[] args)
            {
                int n = int.Parse(args[0]);
                int i=0;
                Console.Write("{0}\n{1}", string.Join("\n", 
                   new int[n].Select(r => new string('*',i * 2 + 1)
                   .PadLeft(n+i++)).ToArray()),"*".PadLeft(n));
            }
       }

170 charcters.

int n=int.Parse(a[0]);int i=0;Console.Write("{0}\n{1}",string.Join("\n",Enumerable.Repeat(0,n).Select(r=>new string('*',i*2+1).PadLeft(n+i++)).ToArray()),"*".PadLeft(n));

Answer 17

Language: python, no tricks, 78 chars

import sys
n=int(sys.argv[1])
for i in range(n)+[0]:print' '*(n-i)+'*'*(2*i+1)

Answer 18

Language: Java, Char count: 219

class T{ /* 219 characters */
  public static void main(String[] v){
    int n=new Integer(v[0]);
    String o="";
    for(int r=1;r<=n;++r){
      for(int s=n-r;s-->0;)o+=' ';
      for(int s=1;s<2*r;++s)o+='*';
      o+="%n";}
    while(n-->1)o+=' ';
    System.out.printf(o+"*%n");}}

For reference, I was able to shave the previous Java solution, using recursion, down to 231 chars, from the previous minimum of 269. Though a little longer, I do like this solution because T is truly object-oriented. You could create a little forest of randomly-sized T instances. Here is the latest evolution on that tack:

class T{ /* 231 characters */
  public static void main(String[] v){new T(new Integer(v[0]));}}
  String o="";
  T(int n){
    for(int r=1;r<=n;++r){
      x(' ',n-r);x('*',2*r-1);o+="%n";}
    x(' ',n-1);
    System.out.printf(o+"*%n");
  }
  void x(char c,int x){if(x>0){o+=c;x(c,x-1);}
 }

Answer 19

Groovy 62B

n=args[0]as Long;[*n..1,n].any{println' '*it+'*'*(n-~n-it*2)}

_

n = args[0] as Long
[*n..1, n].any{ println ' '*it + '*'*(n - ~n - it*2) }

Answer 20

Language: C, Char count: 133

Improvement of the C-version.

char s[61];

l(a,b){printf("% *.*s\n",a,b,s);}

main(int i,char**a){
  int n=atoi(a[1]);memset(s,42,61);
  for(i=0;i<n;i++)l(i+n,i*2+1);l(n,1);
}

Works and even takes the tree height as an argument. Needs a compiler that tolerates K&R-style code.

I feel so dirty now.. This is code is ugly.

Answer 21

AWK, 86 characters on one line.

awk '{s="#";for(i=0;i<$1;i++){printf"%"$1-i"s%s\n","",s;s=s"##"}printf"%"$1"s#\n",""}'

echo "8" | awk '{s="#";for(i=0;i<$1;i++){printf"%"$1-i"s%s\n","",s;s=s"##"}printf"%"$1"s#\n",""}'
        #
       ###
      #####
     #######
    #########
   ###########
  #############
 ###############
        #

cat tree.txt
3
5

awk '{s="#";for(i=0;i<$1;i++){printf"%"$1-i"s%s\n","",s;s=s"##"}printf"%"$1"s#\n",""}' tree.txt
   #
  ###
 #####
   #
     #
    ###
   #####
  #######
 #########
     #

Answer 22

Language: C, Char count: 176 (2 relevant spaces)

#include <stdio.h>
#define P(x,y,z) for(x=0;x++<y-1;)printf(z);
main(int c,char **v){int i,j,n=atoi(v[1]);for(i=0;i<n;i++){P(j,n-i," ")P(j,2*i+2,"*")printf("\n");}P(i,n," ")printf("*\n");}

Answer 23

Language: Python, Significant char count: 90

It's ugly but it works:

import sys
n=int(sys.argv[1])
print"\n".join(" "*(n-r-1)+"*"*(r*2+1)for r in range(n)+[0])

...

$ python tree.py 13
            *
           ***
          *****
         *******
        *********
       ***********
      *************
     ***************
    *****************
   *******************
  *********************
 ***********************
*************************
            *

Answer 24

Since this is a CW: I don't like that code golfs are always organized in terms of "number of characters" or somesuch. Couldn't they be organized in terms of number of instructions for the compiler/interpreter (or some similar criterion)? Here is the Ruby solution again, and it's basically the same, but now for human consumption too:

SPACE = " "
ASTERISK = "*"
height_of_tree=ARGV[0].to_i
tree_lines = (1..height_of_tree).to_a
tree_lines.push 1 # trunk
tree_lines.each do | line |
   spaces_before = SPACE*(height_of_tree-line)
   asterisks = ASTERISK*(2*line-1) 
   puts spaces_before + asterisks
end

Answer 25

PHP, 111 chars

(The very last char should be a newline.)

<?php $n=$argv[1];for($r='str_repeat';$i<$n;$i++)echo $r(' ',$n-$i).$r('*',$i*2+1)."\n";echo $r(' ',$n).'*' ?>

Readable version:

<?php

$n = $argv[1];

for ($r = 'str_repeat'; $i < $n; $i++)
    echo $r(' ', $n - $i) . $r('*' , $i * 2 + 1) . "\n";

echo $r(' ', $n) . '*'

?>

Answer 26

Shell version, 134 characters:

#!/bin/sh
declare -i n=$1
s="*"
for (( i=0; i<$n; i++ )); do
    printf "%$(($n+$i))s\n" "$s"
    s+="**"
done
printf "%$(($n))s\n" "*"

Answer 27

C# - Recursion

using System;

class A
{
    static string f(int n, int r)
    {
        return "\n".PadLeft(2 * r, '*').PadLeft(n + r) 
            + (r < n ? f(n, ++r) : "*".PadLeft(n));
    }

    static void Main(string[] a)
    {
        Console.WriteLine(f(int.Parse(a[0]), 1));
    }
}

177 chars (not as short the other C# method posted, but a different way of doing it).

Answer 28

Language: Erlang, Char count: 183 (2 relevant spaces)

Here is an Erlang version, ~181chars:

-module (x).
-export ([t/1]).

t(N) ->
	t(N,0).
t(0,N) ->
	io:format("~s~s~n",[string:copies(" ",N),"*"]);
t(H,S) ->
	io:format("~s~s~n",[string:copies(" ",H),string:copies("*",(S*2)+1)]),
	t(H-1,S+1).

(btw, happy Christmas to everyone!)

Answer 29

Language: Scala, Char count: 128 (1 relevant space)

My Scala version. I'm glad I have found the * operator for strings (String implicitly promoted to RichString).

  def tree(n:Int) {
    def vals(n:Int,k:Int) = ((1 to n) map { i => (k - i, (i * 2) - 1) }).toList
    for(j <- vals(n,n) ::: vals(1,n)) 
      println(" " * j._1 + "*" * j._2)
  }

Answer 30

Language: Nemerle+Nextem, Char count: 129 (1 relevant space)

Nemerle with Nextem:

type s=string;
module t {
    public Main(a : array[s]) : void {
    	def t = int.Parse(a[0]);
    	def x(i) { print s(' ',t-i) + s('*',i*2+1) }
    	$[0..t].Iter(x);
    	x(0)
    }
}

Char count: 128

Edit: Made it take an arg Edit2: Imperative now