100
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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 minimum value of 3, and a maximum value 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 White Spaces 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 PPCG!

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108 Answers 108

1
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Golfscript - 27 chars

~:i,0+{.i\-(' '*\.)+'*'*n}%

~:i  # eval the command line arg, store in i  
,0+  # create a list [0..i-1] add 0 to the end  
{}%  # map this block over the list  
.    # make a copy of the list element 
i\-  # subtract the list element from i 
(    # decrease by one more  
' '* # multiply the result by ' '
\    # swap, so the list element is back on top of stack
.)+  # duplicate, add one, add the two numbers together
'*'* # multiply the result by '*'
n    # put a newline here
| improve this answer | |
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  • \$\begingroup\$ nice, i did mine before seeing yours, was about to refactor it to look like this \$\endgroup\$ – Claudiu Jun 10 '10 at 6:29
1
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Q, 54

{-1(-:)[((x+(!)x),x)]$(((&)((!)(2*x))mod 2),1)#\:"*";}

example:

q){-1(-:)[((x+(!)x),x)]$(((&)((!)(2*x))mod 2),1)#\:"*";} 10
         *
        ***
       *****
      *******
     *********
    ***********
   *************
  ***************
 *****************
*******************
         *
| improve this answer | |
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1
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This is my first experience with code golf. So advices are welcome :)

C: 170 chars:

int main(){
    int n,m=1,x;
    scanf("%d",&n);x=2*n-1;
    for(;m<x*n+n+2;m++)
        printf("%c",m==x*n|m==x*n+n+1?42:m==x*n+1?10:m>x*n?32:!(m%(2*n-1))?10:!(m%x<n-m/x)&m%x<m/x+n+1?42:32);
}
| improve this answer | |
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1
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It's in PHP.

<center><?$t=$_GET[1]*2-$i=1;while($i<=$t){echo str_repeat('*',$i).'<br>';$i+=2;}echo'*'?><center>

Total characters(with spaces):98 Total characters(with no spaces):97 Bytes:98

| improve this answer | |
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1
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I did not see a solution using R. The code below may not be efficient, but it seems to work (170 characters with spaces if all code placed on one line):

for(i in 1:4){ cat( paste( paste(rep(' ', (3-(i-1))), collapse=''), 
                           paste(rep('*', (2*i-1)),   collapse=''), collapse=''),  
               sep='\n'); if(i==4) cat('    *    ', sep='\n')}


    *
   ***
  *****
 *******
    *
| improve this answer | |
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1
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Javascript, 89

i=4
c=t=""
while(i){o=c,j=(i--+1)*2-3
while(j--)o+="*"
t=o+"\n"+t
c+=" "}console.log(t+o)

Javascript 81

o=s=''
for(a=3;a--;){l=s+=' '
for(k=a*2+1;k--;)l+='*'
o=l+'\n'+o}console.log(o+l)
| improve this answer | |
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1
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><>: 136 chars

This one's not going to win, but because Christmas is coming again, I thought fish needed a Christmas tree too! (pun intended)

1-:&1$>:> :1(?!v~$:> :1(?!vv
        ^-1o" "<   ^-1o"*"<>~2+$1-:0(?!v~~&ao>" "o1-v
      ^                              oa<;o"*"^!?(1: <

It can be run as follows with the standard interpreter:

./fish.py christmas.fish -v 5

... for N=5. (If the file is called christmas.fish :P) In this way, one prepopulates the stack with the value 5. This is the closest I could get to a command-line argument.

| improve this answer | |
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1
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JavaScript, 110 characters (2 relevant spaces)

function p(l)
{
    o=''
    for(c=0; c<=n+l; c++)
      o += c < n - l ? ' ' : '*'
    print(o)
}

n = parseInt(arguments[0])

for(l = 0; l < n; l++)
  p(l)
p(0)

Ran using spidermonkey. $ smjs christmas_tree.js 4

For Javascript Console 105

function p(l){o='';for(c=0;c<=n+l;)o+=c++<n-l?' ':'*';console.log(o)}n=+prompt();for(l=0;l<n;)p(l++);p(0)
| improve this answer | |
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1
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Scala, 73 chars

val n=args(0).toInt
(1 to n):+1 foreach(i=>println(" "*(n-i)+"*"*(2*i-1)))

run as

golf.scala 10
| improve this answer | |
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  • \$\begingroup\$ Wait, does that display the trunk? \$\endgroup\$ – Johannes Kuhn Dec 12 '13 at 19:56
  • \$\begingroup\$ yes, :+1 would do that \$\endgroup\$ – prashanth Dec 12 '13 at 20:05
1
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Python 2 - 62 Bytes:

i,x=input()*2,1
exec"print('*'*(x%i)).center(i);x+=2;"*(i/2+1)

Multiplying the input by two saves a byte because of the need for extra brackets.
There may be a way to further golf the operations.

| improve this answer | |
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1
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Japt, 11 bytes

õ_ç* êÃp* û

Try it online!

| improve this answer | |
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1
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Japt -R, 11 bytes

ÇÑÄ î*Ãp* û

Try it

Ç               :Map the range [0,input)
 Ñ              :  Multiply by 2
  Ä             :  Add 1
    î*          :  Repeat * that many times
      Ã         :End map
       p*       :Push a *
          û     :Centre pad each element with spaces to the length of the longest
                :Implicitly join with newlines
| improve this answer | |
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1
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Lua, 100 99 bytes

p,r,n=io.write,('').rep,arg[1]for i=0,n do p(r(' ',n-i+1),r('*',i*2+1),'\n')end p(r(' ',n+1),'*\n')

Try it online!

Another Lua version, a little shorter.

| improve this answer | |
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  • \$\begingroup\$ Thanks! Good catch! \$\endgroup\$ – cyclaminist Dec 23 '18 at 11:49
1
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PHP, 79 bytes

while($argn)echo$r[]=str_pad("
",1+$argn--).str_pad("",++$n*2-1,"*");echo$r[0];

Run as pipe with -nR or try it online.

| improve this answer | |
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  • \$\begingroup\$ Save 2 bytes using variable variables: Try it online! \$\endgroup\$ – Night2 Oct 13 '19 at 13:50
1
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Zsh, 77 64 bytes

Since all these old questions are now open, I think the oldest q. on codegolf.se needs a zsh answer!
Try it Online!

s=*;for ((;i<$1;))printf %$[$1+i++]s\\n $s&&s+=**
printf %$1s \*

Hat-tip to Alastair from Boxing Day 2008
NB: Putting the printf stuff in a function is no advantage...
NB2: original for 77 bytes.. saved 12 bytes by eliminating quotes, braces, trailing newline

| improve this answer | |
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1
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Charcoal, 12 bytes

G<N*‖↑¶M⊖θ←*

Try it online

explanation

G<N*             #Draw a triangle size input N with character "*"
      ‖↑           #Mirror the triangle so it is the right way round
        ¶          #Newline
         M⊖θ←    #move left input-1 
               *   #"*" character
                   #the result is implicitly printed
| improve this answer | |
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  • \$\begingroup\$ Nice answer! I took the liberty of creating a TIO link so others can see it in action, if you'd liked to edit it into your post: tio.run/##ASkA1v9jaGFyY29hbP//… \$\endgroup\$ – Malivil Dec 19 '19 at 18:25
  • \$\begingroup\$ my bad @Malivil! I meant to add one, but forgot, thank you :) \$\endgroup\$ – mabel Dec 19 '19 at 18:33
1
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Keg, 42 38 32 23 bytes

:&1ɧ1⑷:⑻$-⑬*$⑵;`*`*⑸(
'

Try it online!

-9 bytes due to generating odd numbers inside of the map

Answer History

32 Bytes

¿&1(⑻|:2+)1^⑷:;½ℤ⑻$-⑬*^`*`*⑸(,
,

Try it online!

-6 bytes due to using a mapping approach

38 Bytes

:&®l1(©l|⑬©l*,:`*`*,
,2+©l;®l)&⑬*,`*`,

-4 bytes due to operator (space string)

Funny story: I almost said this was 40 bytes before I realised that I forgot how to count.

Try it online!

I might as well place up the Keg Christmas tree for the year seeing as how it's almost December!

Explained

:&®l    #Store the amount of lines in variable l and the register
1   #Push the number of stars per row
(©l|    #Repeat variable l times
    ⑬©l*,   #Print that amount of spaces
    :`*`*,  #Print that amount of stars

    ,   #Print a literal newline
    2+  #Increment the number of stars
    ©l;®l   #Update the amount of spaces to print
)
&⑬*,`*`,    #Print the bottom row
| improve this answer | |
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1
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Java, 180 chars

interface a{static void main(String[]a){for(int N=new Byte(a[0]),i=-1;i++<N;p('*',i%N*2),p('\n',0))p(' ',N-i%N-1);}static<T>void p(T c,int i){System.out.print(c);if(i-->0)p(c,i);}}

I believe this is a new record for Java for this question!

interface a
{
    static void main(String[]a){
        for(int N=new Byte(a[0]),i=-1;i++<N;p('*',i%N*2),p('\n',0))p(' ',N-i%N-1);
    }
    static<T>void p(T c,int i){
        System.out.print(c);
        if(i-->0)p(c,i);
    }
}

This program uses a recursive method to get rid of unnecessary for loops and print calls. Everything in main is run in one for loop.

| improve this answer | |
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  • 1
    \$\begingroup\$ The whitespace is there to make it easier to read. The 180 char count is for the necessary characters only. \$\endgroup\$ – Ethan Gallagher Apr 30 at 2:37
  • 1
    \$\begingroup\$ Nice. I see that you have already included the reduced version as well. That would have been what I suggested, and it is generally best to include both versions. \$\endgroup\$ – Wheat Wizard Apr 30 at 3:39
1
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Batch, 132 129 bytes

@!! 2>nul||cmd/q/v/c%0 %1&&exit/b
for /l %%X in (1 1 %1)do set[= ![!
set]=![!*
:*
echo%]%
set]=%]:~1%**
2>x goto:*%]:~1%&echo%[%*

I shamelessly copied Golfing Delayed Expansion Variables in Batch to my batch script.
Uses the bizarre ability of GOTO :NUL to

allow execution of concatenated commands in the context of the caller

Edit 2020/5/1: Abused token delimiters to shorten variable names

| improve this answer | |
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1
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MAWP, 45 bytes

=M@![![32;1-]`M[42;1-]`M2+=M10;1-]`[32;1-]42;

Try it!

Takes a while for N bigger than 10

| improve this answer | |
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1
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Rockstar, 107 bytes

listen to N
X's0
while N-X
let X be+1
let Y be N-X
let Z be X*2-1
say " "*Y+"*"*Z

let N be-1
say " "*N+"*"

Try it here (Code will need to be pasted in)

| improve this answer | |
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  • \$\begingroup\$ A good idea would be to append the name of a related rock song to each of your rockstar programs. \$\endgroup\$ – Razetime Sep 23 at 16:56
  • \$\begingroup\$ Not a bad idea, @Razetime, I might just do that - I already use song names for all my challenge titles. Of course, if I was anyway skilled at such things, I'd actually write a song in Rockstar related to the challenge! \$\endgroup\$ – Shaggy Sep 23 at 16:59
1
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sed 4.2.2, 62 bytes, -r flag

s/0\B/ /g
:
H
s/ (0+)/0\10/
//b
:a
s/0(0+)0/ \1/
ta
H
x
y/0/*/

Takes input in unary (e.g. 3 is 000), allowed as per meta consensus.

Try it online!

With comments:

#Replace all zeroes except the last by a space
s/0\B/ /g
#Unnamed branch label
:
#Append to hold buffer
H
#Put zeroes around a stretch of zeroes
s/ (0+)/0\10/
#Jump to unnamed label if there are any spaces left
//b
#Create a label a, and recursively remove initial/final zeroes
:a
s/0(0+)0/ \1/
ta
#Append to hold buffer
H
#Exchange hold/pattern buffers
x
#Replace 0s with asterisks
y/0/*/
| improve this answer | |
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0
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First try in LUA

f=string.rep p=print function t(N) for i=0,N do s=f(" ",N-i) p(s..f("+",2*i-1)..s) end p(f(" ",N-1).."+"..f(" ",N-1)) end t(arg[1])

After selecting all of it scite tells me these are 131 chars

For clarities sake without optimizing away the \n etc:

f=string.rep 
p=print 
function t(N) 
 for i=0,N do 
   s=f(" ",N-i)
   p(s..f("+",2*i-1)..s)
 end 
  p(f(" ",N-1).."+"..f(" ",N-1)) 
end 
t(arg[1])

For the python version by ΤΖΩΤΖΙΟΥ I get shown 115 chars... Hrm, some more things to optimize

| improve this answer | |
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  • 1
    \$\begingroup\$ Note: all insignificant/irrelevant whitespace should be ignored, as per the question specifications. So, any beautifying/syntax-needed whitespace doesn't count, but a " " literal does count. So your fully expanded version has 119 chars (3 significant spaces) \$\endgroup\$ – tzot Dec 25 '08 at 20:06
0
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Scala, 97 chars

This one gets n from command line.

Thanks to ΤΖΩΤΖΙΟΥ for the * operator

val n=args(0).toInt*2
(1.until(n,2))foreach{i=>println(" "*(n-i)+"* "*i)}
println (" "*(n-1) + "*")
| improve this answer | |
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0
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Language: Erlang, Char count: 151

A little bit shorter Erlang version:

-module(x).
-export([t/1]).
t(N)->[H|_]=T=t(N,1),io:format([T,H]).
t(0,_)->[];t(N,M)->[[d(N,32),d(M,42),10]|t(N-1,M+2)].
d(N,C)->lists:duplicate(N,C).

When should run with command line argument

-module(x).
-export([t/1]).
t([N])->[H|_]=T=t(list_to_integer(N),1),io:format([T,H]),init:stop().
t(0,_)->[];t(N,M)->[[d(N,32),d(M,42),10]|t(N-1,M+2)].
d(N,C)->lists:duplicate(N,C).

Invocation:

$ erl -noshell -noinput -run x t 11
           *
          ***
         *****
        *******
       *********
      ***********
     *************
    ***************
   *****************
  *******************
 *********************
           *
| improve this answer | |
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0
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Rhino Javascript shell: 117 chars minified

t=['*'];
for(i=1;i<arguments[0];++i)
{
  s='*'+t[i-1]+'*';
  for(j in t) 
    t[j]=' '+t[j];
  t[i]=s;
}
t[i]=t[0];print(t.join('\n'));

minified:

t=['*'];for(i=1;i<arguments[0];++i){s='*'+t[i-1]+'*';for(j in t) t[j]=' '+t[j];t[i]=s;}t[i]=t[0];print(t.join('\n'));

results:

c:\>java -jar C:\appl\Java\rhino1_7R1\js.jar c:/tmp/Xtree.js 10
         *
        ***
       *****
      *******
     *********
    ***********
   *************
  ***************
 *****************
*******************
         *
| improve this answer | |
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0
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Language: FoxPro 2.x for DOS (should work with Clipper too), Char count: 62

para n
for h=1 to n
?spac(n-h)+repl('*',2*h-1)
endf
?spac(n-1)+'*'
| improve this answer | |
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0
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Language: Euphoria 147 chars (9 relevant spaces):

include get.e
object
    a = command_line(), 
    t = 42
a = value( a[3] )
a = a[2]
for i = 1 to a do
    puts(1, repeat( 32, a - i ) & t & 10)
    t &= "**"
end for
puts(1, repeat( 32, a - 1 ) & 42 & 10 )

With only relevant whitespace:

include get.e
object a=command_line(),t=42a=value(a[3])a=a[2]for i=1to a do puts(1,repeat(32,a-i)&t&10)t&="**"end for puts(1,repeat(32,a-1)&42&10)
| improve this answer | |
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0
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Excessively long version in J (97 chars)

t=:3 :0
d=:0
k=:''
while.d<y
do.
k=:k,((d{((y-1)+>:i.y))$!.'*'((d{((|.i.y)))$,' ')),LF
d=:d+1
end.k,y$k
)

Run it this way:

t N

where N is tree height.

And Merry Xmas (a bit late).

| improve this answer | |
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0
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Here's a Ruby Newbie (ha! It rhymes!) with his first working solution:

Ruby 164 characters (of readable code)

n=gets.to_i-1
(0..n).each do |j|  
    (n-j).times do 
        print " "
    end 
    (1+j*2).times do
        print "*" 
    end
    print "\n"
end
n.times do 
    print " "
end
print "*"
| improve this answer | |
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