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 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!

Answer 1

05AB1E, 9 bytes

LĆ'*×j€û»

Try it online or verify all Christmas trees in the range [3, 30].

€û» can alternatively be ».º for the same byte-count: try it online.

9 bytes alternative:

·ÅÉĆ'*×.c

Try it online or verify all Christmas trees in the range [3, 30].

Explanation:

L          # Create a list in the range [1, (implicit) input]
           #  i.e. 3 → [1,2,3]
 Ć         # Enclose; appending its own head
           #  → [1,2,3,1]
  '*×     '# For each value, repeat the "*" that many times as string
           #  → ["*","**","***","*"]
     j     # Prepend spaces to make all items of a length equal to the (implicit) input
           #  → ["  *"," **","***","  *"]
      €û   # Palindromize each string
           #  → ["  *  "," *** ","*****","  *  "]
        »  # Join the list by newlines
           #  → "  *  \n *** \n*****\n  *  "
           # (after which it is output implicitly as result)

·          # Double the (implicit) input-integer
           #  i.e. 3 → 6
 ÅÉ        # Pop and push a list of all odd numbers <= this integer
           #  → [1,3,5]
   Ć       # Enclose; appending its own head
           #  → [1,3,5,1]
    '*×   '# For each value, repeat the "*" that many times as string
           #  → ["*","***","*****","*"]
       .c  # Centralize it by adding leading spaces (which implicitly joins by newlines)
           #  → "  *\n ***\n*****\n  *"
           # (after which it is output implicitly as result)

Answer 2

K (oK), 33 29 bytes

{(x+1)#(-x+!x)$(1+2*!x)#'"*"}

-4 thanks to streetser!

Try it online!

Answer 3

Charcoal, 9 bytes

Ｇ↗↘←Ｎ*Ｍ↓*

Try it online!

Verbose

Polygon(:UpRight, :DownRight, :Left, InputNumber(), "*")
Move(:Down)
Print("*")

Try it online!

Answer 4

><>, 67 bytes

1:{:v :,2+1{1p461<
v!?:<-1o*84
\~$
>:?!v67*o1-
+:}}\0?;~ao1-::?!v{2

Try it online!

Answer 5

Scala 3, char count 132 124

@main def t(n:Int)={def p(i:Int,j:Int):Unit={println(" "*i+"*"*j);if(i==0)println(" "*(j/2)+"*");else p(i-1,j+2);};p(n-1,1)}

Readable version

@main def t(n:Int) = 
  def p(i:Int, j:Int):Unit = 
    println(" " * i + "*" * j)
    if (i == 0) println(" " * (j / 2) + "*")
    else p(i - 1, j + 2)
  p(n - 1, 1)

Results

scala xmastree.scala 3
  *
 ***
*****
  *

scala xmastree.scala 5
    *
   ***
  *****
 *******
*********
    *

Answer 6

Here's how I would do it in Python, very straightforward, only 103 characters:

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

Answer 7

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 8

Common Lisp, 117 essential characters:

(defun x (n)
  (dotimes (v n)
    (format t "~v:@<~v{*~}~>~%"
            (1- (* 2 n))
            (1+ (* 2 v))
            '(())))
  (format t "~v:@<*~>~%" (1-(* 2 n)))

Are there any format gurus out there who know a better way to get repeating arbitrary characters?

Answer 9

Java version. 189 character

class P
{
	static String p(int n, String s) 
	{
		return --n < 1 ? s : p(n, s) + s;
	}

	public static void main(String[] a) 
	{
		for (int N = new Integer(a[0]), i = -1; i++ < N;) 
			System.out.println(p(N - i % N, " ") + p(i % N * 2 + 1, "*"));
	}
}

Answer 10

Windows Batch File

Windows batch files have poor support for string operations: they can concatename, extract and replace strings, but generation of arbitrary-length strings according to a certain pattern AFAIK can only be done via loops. This is how Zach Scrivena's solution works.

However, one can notice that the N+1-th tree line can be generated from the N-th line by cutting one leading space off and adding two traling asterisks, which pretty much simplifies the task. Also, the tree truck repeats the tree top so we can re-use that string to get rid of a few extra loops. So, here's my batch file that uses these two tricks (165 characters):

@echo off
setlocal enableextensions enabledelayedexpansion
set s=
for /l %%i in (1,1,%1)do set s= !s!
set t=!s!*
for /l %%i in (1,1,%1)do echo !t!&set t=!t:~1!**
echo %s%*

Assuming that echo is already off and command extensions and delayed variable expansion are on, we can drop the first two lines and shorten the code down to 108 characters.

Usage:

> xmastree.bat 7 & pause
       * 
      *** 
     ***** 
    ******* 
   ********* 
  *********** 
 ************* 
       *

Answer 11

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 12

Haskell - 105 95 characters - 3 Relevant spaces

Improved on the other Haskell solution (https://codegolf.stackexchange.com/a/4267/7353) by 2 12 strokes.

• Updated take x$cycle "*" into replicate x '*'
• Removed unnecessary brackets

Updated version:

r=replicate;main=(\x->mapM_ putStrLn[r(x-l)' '++r(l+l-1)'*'|l<-[1..x]++[1]])=<<(readLn::IO Int)

Previous version:

c=cycle;main=(\x->mapM_ putStrLn[(take(x-l)$c" ")++(take(l+l-1)$c"*")|l<-[1..x]++[1]])=<<(readLn::IO Int)

Readable (updated) version:

main=(\ size->
          mapM_
               putStrLn
               [replicate (size - count) ' ' ++ replicate (count + count - 1) '*' | count <- [1..size] ++ [1]]
     ) =<< ( readLn :: IO Int )

Haskell is such an elegant language.

Answer 13

K 33

q)k)f:{{(|:'x),'1_'x}x$(1+(!x),0)#'"*"}
q)f 4
"   *   "
"  ***  "
" ***** "
"*******"
"   *   "

Answer 14

Python - 104 / 94 characters

Alright, so I have two solutions here. One of them is, I guess, a bit "trickier", placing all of the code on one line, while the other solution is actually shorter.

import sys
c=int(sys.argv[1])
for i in range(c+2):print" "*(c-1)+"*"if i==c+1 else" "*(c-i)+"*"*(2*i-1)

That's the 104-char version. Who said python is always readable? It doesn't use any "tricks" though, which is a plus, I guess? If we split the if/else statement onto a seperate line like so:

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

...this is much neater and is actually a few characters shorter.

Answer 15

JavaScript (ES6), 58 bytes

f=(n,s=`*
`,l)=>n?(k=' '.repeat(--n)+s)+f(n,'**'+s,l||k):l

Demo

f=(n,s=`*
`,l)=>n?(k=' '.repeat(--n)+s)+f(n,'**'+s,l||k):l

console.log(f(7))

Answer 16

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.

Answer 17

Python 2, 56 bytes

i=n=input()
exec"i=~-i%n;print' '*i+'*'*(n*2-i+~i);"*-~n

Try it online!

Answer 18

Perl 6, 39 bytes

{say " "x$^a-$_,\*x$_*2-1 for 1...$a,1}

Try it online!

It's one of those questions, where it's easier to just print the lines in the code block.

Explanation:

{say " "x$^a-$_,\*x$_*2-1 for 1...$a,1}
{                                     }   # Anonymous code block
                          for 1...$a,1    # Loop over 1 to n and 1 again
 say                                      # Print
     " "x$^a-$_                           # Leading spaces
               ,\*x$_*2-1                 # And then the amount of asterisks

Answer 19

05AB1E (legacy), 16 10 bytes

L·<'**Ć.c»

Try it online!

Explanation:

L·<'**Ć.c»
L          : Create a range [1..input]
 ·<        : 2n-1 every element
   '**     : Multiply every element with "*"
      Ć    : Append the first element to the end
       .c  : Centralize elements
         » : Print out with newlines

Previous solution:

µ¾·>'**¼})Ć.c»

Try it online!

Explanation:

µ¾·>'**I¾-ú¼})Ć»
 ¾·>'**I¾-ú      : Create the row with padding and push to stack
           ¼     : Increment the counter
µ           }    : Loop until the counter reaches the input
             )   : Enclose stack to a list
              Ć  : Append the head to the end
               » : Print out the stack with newlines

Answer 20

Bash: 126120

As there is no bash purpose, there is one:

for((z=$1-1;z;z--)){ printf -v s "%$((($1-z)*2-1))s" ""
printf "%$((2*$1-z))s\n" "${s// /*}";};printf "%$((1+$1))s\n" \*

This could be written:

#!/bin/bash
               #
              for\
            ((z=$1-
          1;z;z--));do
        printf -v s "%$((
     ($1-z)*2-1))s" "" #fil
   printf "%$((2*$1-z))s\n" \
 "${s// /*}";done;printf "%$((1
          +$1))s\n"\
              \*
              ##

In use:

set -- 12
for((z=$1-1;z;z--)){ printf -v s "%$((($1-z)*2-1))s" ""
printf "%$((2*$1-z))s\n" "${s// /*}";};printf "%$((1+$1))s\n" \*
            *
           ***
          *****
         *******
        *********
       ***********
      *************
     ***************
    *****************
   *******************
  *********************
            *

Or into the script:

./chrismas.sh 6
      *
     ***
    *****
   *******
  *********
      *

Answer 21

Intel 4004 machine code, 59 bytes

This 4-bit chip was the first commercial microprocessor, introduced in 1971. Multiplication and division were performed in software, and the accumulator could not be copied to one of the 16 registers except by swapping values.

40 33 50 0F A0 F8 B0 A0 1C 02 A1 B0 50 0F C0 24
20 A0 F8 50 2B 24 2A A1 90 F5 50 2B 24 20 A0 F8
50 2B 24 0C 53 E0 24 0D 53 E0 C0 14 32 53 E0 F8
40 2B C0 53 F0 B3 B0 A0 B1 50 02

The assembly code requires this python emulator for meaningful output.

jun start

mainloop:
    jms printline
    ld r0
    dac
    xch r0
    ld r0
    jcn an mainloop
    ld r1
    xch r0
    jms printline
    bbl 0

printline:
    fim r2 32
    ld r0
    dac
    jms printx

    fim r2 42
    ld r1
    sub r0
    ral
    jms printx

    fim r2 32
    ld r0
    dac
    jms printx

    ;carriage return
    fim r2 12
    jms $3e0
    fim r2 13
    jms $3e0

    bbl 0

printx: 
    jcn az ditch
    jms $3e0
    dac
    jun printx
ditch:
    bbl 0

start:
    jms $3f0 ; input
    xch r3
    xch r0 ; running total
    ld r0
    xch r1 ; permanent total
    jms mainloop

Sample run:

$ python intel4004-emu/main.py tree.4004 
8
       *       
      ***      
     *****     
    *******    
   *********   
  ***********  
 ************* 
***************
       *       

Answer 22

Python-3x, 119 bytes

N = int(input())
print(' '*N+'\n','\n'.join(['\t'+' '*(N-i)+'*'*(i*2+1) for i in range(N)]) + '\n', ' '*(N+3)+'*'+'\n')

result:-

enter N value
3
   *
  ***
 *****
   *



 4
        *
       ***
      *****
     *******
        *

9
             *
            ***
           *****
          *******
         *********
        ***********
       *************
      ***************
     *****************
             *

Answer 23

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

Answer 24

Vyxal C, 7 bytes

ʁd›×*×J

Try it Online!

Vyxal, 13 bytes

ɾ×*§↵vøm:⁋₴h,

Try it Online!

Answer 25

jq -r, 47 41 39 bytes

-2 bytes thanks to Michael Chatiskatzi

. as$n|range(.),0|" "*($n-.)+"**"*.+"*"

Try it online! Add 2 bytes if a leading space is not acceptable.

. as$n                                   Store the input number in $n
      |                                  With that number as .
       range(.)                           Numbers from 0 up to one less than .
               ,0                         and also another 0
                 |                       With each of those numbers as .
                     *($n-.)              $n minus . copies of
                  " "                     space
                            +             Concatenate
                                 *.       . copies of
                             "**"         that string
                                   +"*"   Concatenate one more asterisk

The -r flag outputs each of those strings on a separate line without wrapping it in quotes.

Answer 26

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 27

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 28

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

Answer 29

Language: C, Char count: 433 (1 relevant space)

C version. Not short, not pretty, but it works.

#include <stdio.h>

void printLevel(int level, int width)
{
    int i;
    int count = level + (level - 1);
    int spaces = width - count;
    int lowerBound = spaces / 2;
    int upperBound = width - lowerBound;
    for (i = 0; i < width; i++) {
        if (i >= lowerBound && i < upperBound) {
            printf("*");
        } else {
            printf(" ");
        }
    }
    printf("\n");
}

void makeTree(int level)
{
    int i;
    int width = level * 2 - 1;
    for (i = 1; i <= level; i++) {
        printLevel(i, width);
    }
    printLevel(1, width);
}

int main(int argc, char **argv)
{
    int level = atoi(argv[1]);
    makeTree(level);
}

Answer 30

Language: Python, Char count: 104

Another take at python. Note that the question requested for a script, not a function.

import sys
n= int(sys.argv[1])
c= lambda s: s.center(2*n)
print "\n".join(c("*"*(2*i+1)) for i in range(n)); print c("*")

$ py ax 11
          *
         ***
        *****
       *******
      *********
     ***********
    *************
   ***************
  *****************
 *******************
*********************
          *