Print number triangle

Question

Given a number N, output a NxN right angled triangle, where each row i is filled with numbers up to i.

Example

n = 0

(no output)

n = 4

1
1 2
1 2 3
1 2 3 4

n = 10

1
1 2
1 2 3
.
.
.
1 2 3 4 5 6 7 8 9 10

(no alignment needed)

n = N

1
1 2
1 2 3
.
.
.
1 2 3 4 .... N

There is no trailing space at the end of each line.

Least number of bytes wins, and standard loopholes are not allowed.

Answer 1

Joe, 5 3 bytes (+2 or +3 for -t flag)

Well, apparently I didn't utilize the full potential of Joe. This was possible back when I first posted this.

\AR

Here, R gives the range from 0 to n, exclusive. Then \A takes successive prefixes of it (A is the identity function). Examples:

With -t flag (note: this is now the standard output even without the flag):

   (\AR)5
0
0 1
0 1 2
0 1 2 3
0 1 2 3 4
   \AR5
0
0 1
0 1 2
0 1 2 3
0 1 2 3 4
   \AR2
0
0 1
   \AR1
0
   \AR0

Without it:

   \AR5
[[0], [0, 1], [0, 1, 2], [0, 1, 2, 3], [0, 1, 2, 3, 4]]
   (\AR)5
[[0], [0, 1], [0, 1, 2], [0, 1, 2, 3], [0, 1, 2, 3, 4]]
   \AR2
[[0], [0, 1]]
   \AR1
[[0]]
   \AR0
[]

---

The rules got changed a bit. My old code didn't behave correctly with N =0. Also, now output could be just a nested list, so -t can be dropped.

1R1+R

Now, Rn gives a range from 0 to n, exclusive. If given 0, it returns an empty list. 1+ adds 1 to every element of that range. 1R maps the values to ranges from 1 to x. Empty liats, when mapped, return empty lists.

Example output:

   1R1+R0
[]
   1R1+R5
[[1], [1, 2], [1, 2, 3], [1, 2, 3, 4], [1, 2, 3, 4, 5]]

Update: I just noticed something. The function automatically maps to rank 0 elements. The following example is run with -t flag.

   1R1+R3 5 8
1
1 2
1 2 3

1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8

---

Old: 5 bytes (with the -t flag)

1R1R

This is an anonymous function which takes in a number, creates a list from 1 to N (1Rn) and maps those values to the preceding range, giving a range from 1 to x for each item of range 1 to N.

The -t flag gives output as a J-like table.

   1R1R5
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

Note : the language is very new and not complete, but the latest version was released before this challenge.

Answer 2

Python 3, 48 45 bytes

f=lambda n:n and[f(n-1),print(*range(1,n+1))]

Hooray for side effects.

Answer 3

APL, 5

⍪⍳¨⍳⎕

creates a vector 1..n and for each element another such vector.

Then ⍪ makes a column out of all vectors. This avoids the problem with trailing blanks.

Try it on tryapl.org

---

Older solution:

{⎕←⍳⍵}¨⍳⎕

Creates a vector 1..n

{⎕←⍳⍵} is a function that outputs for each (¨) element a vector 1..n on a separate line

This one can't be tried on tryapl.org unfortunately, because ⎕← doesn't work there.

Answer 4

J, 27 bytes

J is not good with non-array numeric output. This function creates a properly formatted string from the numbers.

   ;@(<@,&LF@":@:>:@:i.@>:@i.)

   (;@(<@,&LF@":@:>:@:i.@>:@i.)) 4
1
1 2
1 2 3
1 2 3 4

Try it online here.

Answer 5

PHP, 53 Bytes

Edit 2: Ismael Miguel suggested reading from input instead of defining a function, so the score is now 53 bytes for PHP:

for($a=1;@$i++<$n=$argv[1];$a.=" ".($i+print"$a\n"));

And once again, it can be improved if PHP is configured to ignore errors (52 bytes):

for($a=1;$i++<$n=$argv[1];$a.=" ".($i+print"$a\n"));
for($a=1;$i++<$n=$_GET[n];$a.=" ".($i+print"$a\n"));

---

Edit: Austin suggested a 60 bytes version in the comments:

function f($n){for($a=1;@$i++<$n;$a.=" ".($i+print"$a\n"));}

Which can be improved if we doesn't display PHP errors (59 bytes):

function f($n){for($a=1;$i++<$n;$a.=" ".($i+print"$a\n"));}

$a stores the next line that will be printed, and each time it's printed a space and the next number (print always returns 1) are concatened to it.

---

Recursive functions (65 bytes):

function f($n){$n>1&&f($n-1);echo implode(' ',range(1,$n))."\n";}
function f($n){$n>1&&f($n-1);for(;@$i++<$n;)echo$i,' ';echo"\n";}   // Using @ to hide notices.

Shorter recursive function, with error reporting disabled (64 bytes):

function f($n){$n>1&&f($n-1);for(;$i++<$n;)echo$i,' ';echo"\n";}

Even shorter recursive function, with error reporting disabled and an empty line before real output (62 bytes):

function f($n){$n&&f($n-1);for(;$i++<$n;)echo$i,' ';echo"\n";}

---

Just for fun, non-recursive fucntions:

function f($n){for($i=0;$i<$n;print implode(' ',range(1,++$i))."\n");}    // 70 bytes
function f($n){for(;@$i<$n;print implode(' ',range(1,@++$i))."\n");}      // 68 bytes, hiding notices.
function f($n){for(;$i<$n;print implode(' ',range(1,++$i))."\n");}        // 66 bytes, error reporting disabled.

Answer 6

CJam, 13 12 bytes

ri{),:)S*N}/

How it works:

ri{       }/     "Run the block input number of times with iteration index from 0 to N-1";
   )             "Increment the iteration index (making it 1 to N)";
    ,            "Get an array of 0 to iteration index";
     :)          "Increment each of the above array members by 1";
       S*        "Join all above array numbers with space";
         N       "Add a new line. After all iterations, things are automatically printed";

Try it online here

Answer 7

JavaScript (ES6) 49 52

Such a simple task, I wonder if this can be made shorter in JS (Update: yes, using recursion)

Recursive 49

f=n=>alert((r=w=>n-i++?w+'\n'+r(w+' '+i):w)(i=1))

Iteraive 52

f=n=>{for(o=r=i=1;i++<n;o+='\n'+r)r+=' '+i;alert(o)}

Answer 8

Pyth, 9 bytes

VQjdr1hhN

Really thought that this can be done shorter, but it doesn't seem so.

Try it online.

            Q = input()
VQ          For N in [0, 1, ..., Q-1]:
    r1hhN       create list [1, ..., N+1+1-1]
  jd            print joined with spaces

Answer 9

Java, 85 84 bytes

This is surprisingly short in Java.

void a(int a){String b="";for(int c=0;c++<a;System.out.println(b+=(c>1?" ":"")+c));}

Indented:

void a(int a){
    String b="";
    for(int c=0;
        c++<a;
        System.out.println(
                b+=(c>1?" ":"")+c
        ));
}

1 byte thanks to Bigtoes/Geobits

Answer 10

><> (Fish), 40 37 + 3 = 40 bytes

&1>:&:&)?;1\
(?v:n" "o1+>}:{:@
ao\~1+

Once again, ><> does decently well at another number printing exercise. Run with the -v flag for input, e.g.

py -3 fish.py -v 4

Explanation

&               Put n in register
1               Push 1 (call this "i")

[outer loop]

:&:&)?          If i > n...
;                 Halt
1                 Else push 1 (call this "j")

[inner loop]

}:{:@(?         If j > i...
~1+ao             Pop j, print newline, increment i and go to start of outer loop
:n" "o1+          Else print j, print a space, increment j and go to start of inner loop

Answer 11

Prolog - 119

h(N):-setof(X,(between(1,N,K),setof(Y,between(1,K,Y),X)),[L]),k(L),nl,fail.
k([A|B]):-write(A),(B=[];write(" "),k(B)).

Answer 12

Python 2 - 62 54 65 bytes

def f(n):
 for x in range(n):print' '.join(map(str,range(1,x+2)))

Answer 13

C (with no loops, yeah!) - 72 bytes

b(n,c){if(n){b(n-1,32);printf("%d%c",n,c);}}r(n){if(n){r(n-1);b(n,10);}}

This creates a function r(n) that can be used this way:

main(){ r(5); }

See it in action, here on tutorialspoint.com

It requires a very few tricks easily explained. I think it can be greatly improved.

Answer 14

J, 9 characters

As a tacit, monadic verb.

[:":\1+i.

• i. y – the numbers from 0 to y - 1.
• 1 + i. y – the numbers from 1 to y.
• ": y – the vector y represented as a string.
• ":\ y – each prefix of y represented as a string.
• ":\ 1 + i. y – each prefix of the numbers from 1 to y represented as a matrix of characters.

Answer 15

Python 2 - 72

>>> def p(N):print'\n'.join(' '.join(map(str,range(1,i+2)))for i in range(N))
... 
>>> p(5)
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

Answer 16

Perl, 28

Reads the parameter from stdin.

@x=1..$_,print"@x
"for 1..<>

From the command line:

perl -E'$,=$";say 1..$_ for 1..<>'

but I don't now how to count that (probably between 25 and 29).

Answer 17

tcl, 76

time {set p "";set j 1;while \$j<=[incr i] {set p $p\ $j;incr j};puts $p} $n

Testable on http://rextester.com/FPJXC1708

Is the first line accountable? It is not part of the algorithm, only serves for acquiring input.

Answer 18

Perl 6, 24 bytes

{say ~$_ for [\,] 1..$_}

Answer 19

Jelly, 3 bytes

RRG

How it works:

RRG
R     Inclusive Range, 3 -> [1, 2, 3]
 R    Inclusive Range for all elements, [1, 2, 3] -> [[1], [1, 2], [1, 2, 3]]
  G   Attempt to format as grid

Try it online!

Answer 20

J, 14 bytes

":@>@<@:>:\@i.

Usage:

   f =. ":@>@<@:>:\@i.
   f 5
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

Explanation:

   i.4                      N.B.  i.n = list of numbers up to n
0 1 2 3

   >:@i.4                   N.B.  >:n = increment n
1 2 3 4

   >:\@i.4                  N.B.  >:\n = increment prefixes of n
1 0 0 0
1 2 0 0
1 2 3 0
1 2 3 4

   <@:>:\@i.4               N.B.   < = Box, <@:>:\ = Box the incremented prefixes of n
+-+---+-----+-------+
|1|1 2|1 2 3|1 2 3 4|
+-+---+-----+-------+

   ":@>@<@:>:\@i.4          N.B.   ":@> = String format each opened box (ensures no zeros or spaces appear at the end of each line). 
1
1 2
1 2 3
1 2 3 4

Answer 21

Noether, 39 bytes

Non-competing: Noether is a new language

I~A{A0>}{A(i1+~i(j1+~jP" "P£)"
"P0~ji)}

Try it here!

Explanation:

I~A   - Push User Input onto the stack and store in variable A
{A0>} - If A>0
{     - Then do
A(    - loop until top of stack equals A
i1+~i - Increment i
(     - loop until top of stack equals i
j1+~j - Increment j
P     - Print top of stack (j)
" "   - Push the string " " onto stack
P     - Print top of stack (" ")
£     - Pop top of stack
)     - End loop
"\n"  - Push the string "\n" onto stack
P     - Print top of stack
0~j   - Set variable j to zero
i     - Push i onto stack
)     - End loop

Answer 22

Python

import string
N,s=int(input()),list(string.digits)
for i in range(1,N+1):
    print(' '.join(s[1:i+1]))

Answer 23

Go, 93 81 78 93 90 bytes

func r(n int)(s string){s=string(n+48);if n!=1{s=r(n-1)+" "+s};println(s);return}

Current ungolfed

func r(n int) (s string) {
    // Convert n to a string, we do not have to initialize s since
    // we hijacked the return value.
    // Numbers in the ascii table starts at 48
    s = string(n | 48)
    // Unless we are on our last iteration, we need previous iterations,
    // a space and our current iteration
    if n != 1 {
        // Collect the result of previous iteration for output
        s = r(n-1) + " " + s
    }
    println(s)
    // We can use a naked return since we specified the
    // name of our return value in the function signature
    return
}

If we need to handle N > 9 we can use the following at 78 bytes, however it requires importing the fmt package.

func r(n int)(s string){s=Sprint(n);if n!=1{s=r(n-1)+" "+s};Println(s);return}

If we include the import statement I'm now back at my initial 93 92 90 bytes

import."fmt";func r(n int)(s string){s=Sprint(n);if n>1{s=r(n-1)+" "+s};Println(s);return}

Test it online here: http://play.golang.org/p/BWLQ9R6ilw

The version with fmt is here: http://play.golang.org/p/hQEkLvpiqt

Answer 24

Golfscript 14

,{2+,1>' '*n}/

Expects the input number to be present on the stack.

Online example: link

Answer 25

Perl: 34 characters

print"@$_\n"for map[1..$_],1..$_;

This code gets the input number supplied through the special variable $_.

Answer 26

C, 89 characters

// 90 characters
f(int n){int a=1,b;for(;n--;++a){for(b=0;b<a;++b)printf("%c%d",(!!b)*' ',b+1);puts("");}}

To eliminate confusion about puts("");. This simply prints a newline character (as seen here):

Notice that puts not only differs from fputs in that it uses stdout as destination, but it also appends a newline character at the end automatically (which fputs does not).

I got it slightly shorter with @TheBestOne's java algorithm:

// 89 characters
f(int a){char b[999]="",*p=b+1;int c=0;for(;a--&&(sprintf(b,"%s %d",b,++c)&&puts(p)););}

Answer 27

Clip, 16

Jm[ijkw,1iwS},1n

Explanation

J                   .- join with newlines                           -.
 m[i        },1n    .- map numbers from 1 to numeric value of input -.
    jkw   wS        .- join with spaces                             -.
       ,1i          .- numbers from 1 to index                      -.

Answer 28

Bash+coreutils, 26 bytes

seq $1|sed "x;G;s/\n/ /;h"

• seq simply generates the numbers 1 to n
• sed saves the entire output for a given line in the hold space, and then appends the next line to it.

Answer 29

ZX / Sinclair BASIC - 39 bytes

ZX Basic uses 1 byte per keyword (all the uppercase words), so helps to keep the byte size down a bit...

1 INPUT n:FOR i=1 TO n:FOR j=1 TO i:PRINT j;" ";:NEXT j:PRINT:NEXT i

Using n = 8

Answer 30

R, 28

for(i in 1:scan())print(1:i)

Answer 31

TI-Basic, 28 bytes

Input N
For(I,1,N
randIntNoRep(1,N->L1
SortA(L1
Disp L1
End

Answer 32

Haskell, 62 57 bytes

e=enumFromTo 1
f=putStr.unlines.map(unwords.map show.e).e

Point-free style. Usage example:

Prelude> f 5
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

Answer 33

C++, 130 bytes

To provide N, provide that many arguments on the command-line (the arguments don't matter, just the count of arguments).

#include <stdio.h>
#define printf P
int main(int c, char**){if(int x=c-1){main(x--,0);P("1");for(;x;--x){P(" %d",c-x);}P("\n");}}

Answer 34

C# - 94 bytes

Written as an anonymous function that returns a string, which doesn't seem to be disallowed by the spec.

n=>String.Join("\n\n",Enumerable.Range(1,n).Select(l=>String.Join(" ",Enumerable.Range(1,l))))

Here's an ungolfed version (comments are read in BDCA order):

n =>
    String.Join("\n\n",                    //...then join it together with newlines.
        Enumerable.Range(1, n).Select(l => //For each l from 1 to n, ...
                String.Join(" ",              //...and join it with spaces, ...
                    Enumerable.Range(1, l)    //...get the range from 1 to l, ...

Answer 35

Scala, 73 65 62 bytes

(n:Int)=>print(1 to n map(1 to _ mkString " ") mkString "\n")

Ungolfed

def printNumberTriangle(n: Int): Unit = {
  def rowString(m: Int): String = 1.to(m).mkString(" ")
  print(1.to(n).map(rowString).mkString("\n"))
}

Answer 36

Mathematica, 32

Print@Row[Range@i," "]~Do~{i,#}&

Answer 37

JavaScript, 73

n=5;for(i=1,s='';i<=n;i++)for(j=1;j<=i;j++)s+=j+(j==i?"\n":' ');alert(s);

Answer 38

Excel VBA, 97 bytes

n = InputBox("n")
For i = n To 1 Step -1
For j = n To 1 Step -1
Cells(i, j) = j
Next j
n = n - 1
Next i

When executed you are prompted for n and the resulting triangles are displayed on the spread sheet:

Answer 39

JavaScript, 92 bytes

var x=function(o){for(var r=1;o>=r;r++){for(var a="",f=1;r>=f;f++)a+=f+" ";console.log(a)}};

usage: x(5)

Answer 40

C,88 bytes

f(n,i,j,t){i=j=1;for(;i<=n;){t=j;printf("%d%c",t,j==i?(++i&&(j=1))*'\n':(++j||1)*' ');}}

Usage:

f(10);

1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 10

Answer 41

JavaScript, 77 Bytes

function(n){for(i=1;i<=n;i++){a='';for(j=1;j<=i;j++)a+=j+' ';console.log(a)}}

Answer 42

Pushy, 4 bytes

Non-competing as the language postdates the challenge.

:Lh_

Try it online!

This works by building the stack up to the final line, step-by-step, and printing the stages:

:    \ Input times do (this consumes input):
Lh   \  Push stack length + 1
_    \  Print stack items, space separated.

Answer 43

05AB1E, 3 bytes

LL»

Try it online.

Explanation:

L      # Create a list in the range [1, (implicit) input]
 L     # Map each integer `i` to a list in the range [1, `i`]
  »    # Join the list of lists by newlines,
       # which implicitly also joins the inner lists by a single space
       # (and output it implicitly)

Answer 44

C++

int main()
{
   cout << "Enter N:";
   int N;
   cin >> N;

    for(int i=1; i <= N; i++)
    {
         for(int j=1; j<=i; j++)
            {
              cout << j;
            }
       cout << endl;
    }

  return 0;
}

Answer 45

Python 2 - 60 61 53 bytes

k='1'
for i in range(2,input()+2):print k;k+=' '+`i`

With thanks to Sp3000

Answer 46

Javascript, 83

Not to happpy about this one

n=9;r='';for(i=1;i<n+2;i++){for(a=1;a<i;a++){r+=a+' '}r=r.slice(0,-1)+'\n'}alert(r)

Pretty straight forwards

r=''; so javascript doesn't add the value as numbers

r.slice(0,-1)+'\n'remove last space and add a line end

Edit: info

First I was trying to use A030512(int seq) but that failed n>10

Answer 47

k, 8

1+!:'1+!

I need to add 27 characters so I'm just going to type some nonsense here.

k)!5
0 1 2 3 4

k)1+!5
1 2 3 4 5

k)!:'1+!5
,0
0 1
0 1 2
0 1 2 3
0 1 2 3 4

k)1+!:'1+!5
,1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

Answer 48

Ruby - 51

r=->(n){(1..n).each{|i|puts (1..i).to_a.join(" ")}}

Sample output:

r[5] # 1
     # 1 2
     # 1 2 3
     # 1 2 3 4
     # 1 2 3 4 5

r[7] # 1
     # 1 2
     # 1 2 3
     # 1 2 3 4
     # 1 2 3 4 5
     # 1 2 3 4 5 6
     # 1 2 3 4 5 6 7

Answer 49

VBA, 116 bytes

Function n(m As Integer)
If m > 0 Then 
For a = 1 To m 
n = n & " " & a 
Next 
Debug.Print n(m - 1) 
End If 
End Function

Answer 50

And the loser is... Pascal! 178 148 bytes

Sidenote: this isn't golfed at all, besides newlines and spaces. I haven't coded in Pascal for more than 10 years, so I used it just for the memories.

Golfed:

program p;procedure p(n:integer);var i,j:integer;begin for i:=1 to n do begin for j:=1 to i do begin write(j); end; writeln; end end;begin p(5);end.

Ungolfed:

program p;
procedure p(n:integer);
var i,j:integer;
begin
    for i:=1 to n do begin
        for j:=1 to i do begin
            write(j);
        end;
        writeln;
    end
end;
begin
    p(5);
end.

Answer 51

Python 2 - 57 61 bytes

Had another idea. Only bad thing is the leading space.

def f(n):
 s=''
 for x in range(n):s+=' %s'%(x+1);print s[1:]

example output:

>>> def f(n):
...  s=''
...  for x in range(n):s+=' %s'%(x+1);print s[1:]
... 
>>> f(8)
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8

Answer 52

Golfscript - 41 chars

"#{STDIN.gets}"~.0={}{)}if,{,{)}%" "*}%n*

How it works:

"#{STDIN.gets}" -> Read a string from input

"~" -> Evaluate the input

".0=" -> Create a clone of the input and check if it's zero

"{}{)}if" -> If it's zero, do nothing, else add one to the number

",{,{)}%" "*}%" -> Create a list from 0 to N, loop through it and create new lists and do other stuff that I don't have time to explain.

"n*" -> Display it nicely

Answer 53

ARM assembly 485 bytes

.global main
main:
    mov r0, #10
    mov r1, #1
    bl triangle

    mov r0, #10
    bl putchar

    mov r7, #1
    swi 0

triangle:
    cmp r1, r0
    movgt pc, lr
    push {r0,r1,lr}
    mov r0, r1
    mov r1, #1
    bl row
    mov r0, #10
    bl putchar
    pop {r0,r1,lr}
    add r1, r1, #1
    b triangle

row:
    cmp r1, r0
    movgt pc, lr
    push {r0,r1,lr}
    ldr r0, =numFormat
    bl printf
    pop {r0,r1,lr}
    add r1, r1, #1
    b row

numFormat:
    .asciz "%d "

called using the subroutine triangle, register r0 holds the limit and r1 holds the starting value.

tested on Raspberry Pi and Android

Answer 54

Java 8 - 293 chars

Golfed:

import java.util.stream.*;
import static java.util.stream.Collectors.joining;
public class T{public static void main(String[] a){int n=10;System.out.println(IntStream.range(1,n+1).boxed().map(i->IntStream.range(1,i+1).boxed().map(j->""+j).collect(joining(" "))).collect(joining("\n")));}}

Ungolfed:

    import java.util.stream.*;
    import static java.util.stream.Collectors.joining;

    public class T {
        public static void main(String[] a){
            int n=10;

            System.out.println(
                 IntStream.range(1,n+1)
                          .boxed()
                          .map(i -> IntStream.range(1,i+1)
                                             .boxed()
                                             .map(j -> ""+j)
                                             .collect(joining(" ")))
                          .collect(joining("\n")));
        }
    }

Example output, n = 10:

1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 10

Answer 55

PHP (65 bytes):

This is pretty simple to do in php:

for(;$i++<$_GET[n];$_[]=join(' ',range(1,$i)));echo@join('
',$_);

This probably may output an empty string or the '\0' char or worst if you use 0 (there is no control on it).

This is because $_ will be nullwhen you use 0 and PHP will output null (which may output any of the said before).

---

There is another aproach (61 bytes):

foreach(range(1,$_GET[n])as$v)echo join(' ',range(1,$v))."
";

But it can't handle the 0 in the expected way.

Answer 56

Dyalog APL, 11 characters

Assumes ⎕IO←1.

(⍕↑)⍤0 1⍨⍳⎕

• ⍕⍵ – ⍵ represented as a string.
• ⍺↑⍵ – ⍺ items taken from ⍵.
• ⍺(⍕↑)⍵ – ⍺ items taken from ⍵, the result represented as a string.
• ⍺(⍕↑)⍤0 1⍵ – The previous expression, but executed for each item in ⍺ and each vector in ⍵.
• (⍕↑)⍤0 1⍨⍵ – The previous expression with both arguments taken from ⍵.
• (⍕↑)⍤0 1⍨⍳⍵ – The previous expression applied to the integers from 1 to ⍵.
• (⍕↑)⍤0 1⍨⍳⎕ – The previous expression with input taken from the user.

Answer 57

K, 17 bytes

(`0:" "/$1+!)'1+!

Doing this sort of formatted output isn't very convenient in K. I used the "join" form of / from k5 to join elements of each vector with spaces. Try it with oK.

A nice thing about this solution is that it is in "tacit" form, so there's no need to create a function wrapper. Just append the argument N and suppress the result with ;:

  (`0:" "/$1+!)'1+!5;
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

Answer 58

Powershell v2 number of Characters : 567

   function Build-Triangle 
    {
         [CmdletBinding()]
         param(
            [Parameter(Mandatory=$True,ValueFromPipeline=$True)]
            [int]$n
        )

        begin {}
        process 
        {
            [int]$cnt = 1
            if ( $n -gt 0 )
            {
                while ( $cnt -le $n )
                {
                    $string += $cnt.ToString() + " "
                    Write-Output -InputObject $string
                    $cnt++
                }                
            }
        }
        end {}
    }


    Build-Triangle -n 10 | Measure-Object 
    0 | Build-Triangle 
    11 | Build-Triangle  
    # just for kicks make the triangle upside down
    11 | Build-Triangle  | Sort-Object -Descending
    # find out how big the function is
    Get-Content Function:\Build-Triangle | Measure-Object -Word -Character -Line 

Answer 59

C# - 92 bytes

void f(int n){for(int i=0;i++<n;)Console.WriteLine(string.Join(" ",Enumerable.Range(1,i)));}

Nothing fancy, just a packed function.

Answer 60

JavaScript, 73 chars

Not even trying to compare with the others here, just your typical first post:

for(n=prompt(),i=1;n>=i;i++){var l="";for(j=1;j<=i;j++)l+=" "+j;alert(l)}

Answer 61

PowerShell -  42 32bytes

Edit: AdmBorkBork reports that we can save many bytes by using a complete script, and assuming a default delimiter!

 param($n)0..$n-gt0|%{"$(1..$_)"}

Never done any serious PowerShell, just felt I might learn something from this, and indeed I did. Old 42byte code:

function k($n){0..$n-gt0|%{1..$_-join" "}}

Defines a function k which takes an input $n, creates a range from 0 through to $n, filters for entires greater than 0, then creates a range from 1 to each remaining value, and joins these with a space. Example out:

PS > k 3
1
1 2
1 2 3
PS > k 0
PS >

Alternatively, you can define a filter, which will print as many triangles as you want.

filter z{0..$_-gt0|%{1..$_-join" "}}

PS > 3,0,2|z
1
1 2
1 2 3
1
1 2
PS >

Answer 62

Element, 20

_'[1+2:'.2:`\ ."\
`]

The main idea is that the stacks contain a string and a number. We repeatedly increment the number and append it to the string, printing the result. Given that Element has zero support for arrays, I think this is a very decent score.

Since most people are probably unfamiliar with this language, Element is a golfing language I created in 2012. You can see the most updated interpreter, written in Perl, here.

To make the explanation easier, I'll replace the newline with an L.

_'[1+2:'.2:`\ ."\L`]
_'                    input a number and put it onto the control stack
  [                ]  this is a FOR loop
   1+                 increment the number.  An empty stack is zero.
     2:               make a second copy of it
       '              put one copy on the control stack to save it
        .             append the other copy to the end of the string
         2:           make a second copy of the new string
           `          output one of them
            \ .       append a space to the other
               "      put the number from earlier pack onto the main stack
                \L`   output a newline, but the L should be an actual newline

Answer 63

Python 2, 60 bytes

One byte less than current best in Python 2, so I've decided to post it.

def f(x):
 if x:f(x-1);print" ".join(map(str,range(1,x+1)))

Usage:

f(5)

1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

Answer 64

Three slightly different approaches

Ruby, 37 bytes

f=->n{n.times{|i|puts [*1..i+1]*" "}}

Ruby, 38 bytes

f=->n{puts (1..n).map{|i|[*1..i]*" "}}

Ruby, 40 bytes

f=->n{([*1..n+1]*" ").scan(/ /){puts$`}}

Answer 65

awk, 27 bytes

{for(n=$0;n>=$i=++i;)print}

Got it working with some tweaks.

Example usage and output

me@home:~$ echo 0 | awk '{for(n=$0;n>=$i=++i;)print}'
me@home:~$ echo 1 | awk '{for(n=$0;n>=$i=++i;)print}'
1
me@home:~$ echo 2 | awk '{for(n=$0;n>=$i=++i;)print}'
1
1 2
me@home:~$ echo 12 | awk '{for(n=$0;n>=$i=++i;)print}'
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10 11
1 2 3 4 5 6 7 8 9 10 11 12

Answer 66

UniBasic 50 Bytes

S='';INPUT N;FOR I=1 TO N;S:=I;CRT S;S:=' ';NEXT I

Ungolfed:

S=''
INPUT N
FOR I=1 TO N
  S:=I
  CRT S
  S:=' '
NEXT I

Answer 67

q, 18 bytes

1+til each 1+til n

Answer 68

MATLAB, 63

for m=1:input('');fprintf(['1' repmat(' %d',1,m-1) 10],2:m);end

Not the best, but because of the requirements on spaces, functions like num2str and disp can't be used as they produce too many.

Run the code and enter the number when prompted (~=STDIN). It will then print the number triangle.

Answer 69

MATLAB, 38

@(n)spy(sparse(tril(repmat(1:n,n,1))))

This one is a bit of a wildcard answer. It doesn't print the output, but rather makes a pretty graph. I know this is probably outside the rules, if so refer to my other answer, but I thought I would post this one anyway as it looks quite cool :)