Alphabet Staircase

Question

The Challenge

Your task is to create a program or function that outputs the following with no input:

a
bb
ccc
dddd
eeeee
ffffff
ggggggg
hhhhhhhh
iiiiiiiii
jjjjjjjjjj
kkkkkkkkkkk
llllllllllll
mmmmmmmmmmmmm
nnnnnnnnnnnnnn
ooooooooooooooo
pppppppppppppppp
qqqqqqqqqqqqqqqqq
rrrrrrrrrrrrrrrrrr
sssssssssssssssssss
tttttttttttttttttttt
uuuuuuuuuuuuuuuuuuuuu
vvvvvvvvvvvvvvvvvvvvvv
wwwwwwwwwwwwwwwwwwwwwww
xxxxxxxxxxxxxxxxxxxxxxxx
yyyyyyyyyyyyyyyyyyyyyyyyy
zzzzzzzzzzzzzzzzzzzzzzzzzz

You may use the uppercase alphabet instead of lowercase if you prefer. Trailing/leading newlines or spaces are allowed.

Scoring

This is code-golf, so the shortest answer in each language wins.

Answer 1

Python 2, 36 bytes

i=1
exec'print chr(i+96)*i;i+=1;'*26

Try it online!

Answer 2

05AB1E, 2 bytes

Aƶ

Try it online!

Note that this outputs as a list of lines, as the OP explicitly allowed. The link uses a version with pretty-print (joined by newlines).

How it works

• A yields the lowercase alphabet.
• ƶ lifts the alphabet (multiplies each element by its index).
• » joins by newlines.

Answer 3

APL (Dyalog), 12 8 5 bytes ^SBCS

3 bytes saved thanks to @ngn

4 bytes saved thanks to @Adám

⍴⍨⌸⎕A

OP clarified uppercase letters are valid, as well as output as an array of strings.

Try it online!

How?

⌸ gives us every letter in the ⎕A lphabet with its indexes in it, handed into the function ⍴⍨ with the letter as left argument and the indexes as right argument.

⍴⍨ resha ⍴ es its right argument to the length supplied by its left one. ⍨ switches the left and right (therefore the symbol of it, looking like the face of someone reading this explanation).

Answer 4

Haskell, 27 bytes

[c<$['a'..c]|c<-['a'..'z']]

Try it online! Returns a list of lines. (Thanks to @totallyhuman for pointing out that this is now allowed)

Explanation:

             c<-['a'..'z']  -- for each character c from 'a' to 'z'
[           |c<-['a'..'z']] -- build the list of
[   ['a'..c]|c<-['a'..'z']] -- the lists from 'a' to c, e.g. "abcd" for c='d'
[c<$['a'..c]|c<-['a'..'z']] -- with each element replaced by c itself, e.g. "dddd"

Answer 5

Ruby, 32 30 bytes

-2 bytes thanks to @EricDuminil.

27.times{|n|puts (n+96).chr*n}

Try it online!

Answer 6

brainfuck, 74 bytes

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

Try it online!

Explanation

++++++++[>+>+++>++++++++++++<<<-]>++>++>+>+
TAPE:
  000
  010   C_NEWLINE
  026   V_ITERCOUNT
  097   V_ALPHA
 >001<  V_PRINTCOUNT
  000   T_PRINTCOUNT

V_ITERCOUNT TIMES:      <<[-   

  V_PRINTCOUNT TIMES:     >>[-
    INC T_PRINTCOUNT        >+
    OUTPUT V_ALPHA          <<.
                          >]

  RESTORE V_PRINTCOUNT    >[-<+>]
  INC V_PRINTCOUNT        <+
  INC V_ALPHA             <+
  OUTPUT C_NEWLINE        <<.
                        >]

Try it online!

Answer 7

JavaScript (ES6), 54 bytes

f=(n=9)=>++n<36?n.toString(36).repeat(n-9)+`
`+f(n):''

O.innerText = f()

<pre id=O></pre>

Answer 8

Befunge-98 (FBBI), 27 bytes

1+:0\::'`j'@+\k:$$>:#,_$a,

where  is a substitution character (ASCII 26)

Try it online!

Uses uppercase letters, and has a trailing newline.

Explanation

The code works by storing a counter (0 initially), and on every loop:

• 1+ - Increments it by 1
• :0\:: - Pushes things so that the stack looks like this: bottom [N, 0, N, N, N] top
• '`j'@ - Checks if the counter is greater than 26
  • j'@ - If it is, we jump over the ' and exit using @
  • j'@ - If it isn't, we execute the ', which pushes the ASCII value of @ to the stack

Now the stack looks like this: bottom [N, 0, N, N, 64] top

• +\ - Adds, then switches the top 2: bottom [N, 0, (N+64), N] top The first time through, this is ASCII 65, or A
• k: - Duplicates the second from the top (N+1) times - now there are (N+2) values of (N+64) on the stack (plus the N and 0 from earlier)
• $$ - Throw away the top 2 values - now there are only N values of (N+64)
• >:#,_ - Prints each top value until it gets to a 0 - this means N copies of (N+64) get printed
• $ - Throws away the 0 - Now the stack is just N
• a, - Prints an enter

And it repeats

---

I like how I used the @ both for ending the program and for adding to the counter.

Answer 9

Excel VBA, 38 bytes

Using Immediate Window. :)

[A1:A26]="=REPT(CHAR(96+ROW()),ROW())"

Answer 10

V, 9 bytes

¬az\ÓÎÛäl

Try it online!

Hexdump:

00000000: ac61 7a5c d3ce dbe4 6c                   .az\....l

Answer 11

BASH, 59 54 40 bytes

for l in {a..z};{
a+=a
echo ${a//a/$l}
}

Try it online!

thx. 5 bytes to @Justin Mariner

Answer 12

Ruby, 38 bytes

Returns an Array of strings

->{(a=*?a..?z).map{|x|x*-~a.index(x)}}

-5 bytes thanks to totallyhuman

*-11 bytes thanks to some excellent golfing by Jordan.

Answer 13

MATL, 9 bytes

2Y2"@X@Y"

Try it online!

Explanation

2Y2     % Push string 'abc...z'
"       % For char in that string each
  @     %   Push current char
  X@    %   Push iteration index (1-based)
  Y"    %   Run-length decoding: repeat char that many times
        % Implicit end. Implicit display

Answer 14

Haskell, 31 bytes

-12 bytes thanks to nimi.

zipWith replicate[1..26]['a'..]

Try it online!

This is not a snippet, it is a nullary function (one that takes no arguments) that outputs a list of lines which is allowed because of this meta consensus.

Answer 15

Python 3, 37 bytes

for k in range(27):print(chr(k+96)*k)

Prints a leading newline (which is allowed).

Try it online!

Answer 16

Jelly,  5  4 bytes

^{sneaky Python implementation abuse}

-1 byte thanks to Adám (outputting a list of lines has been allowed; as, now, has writing a function rather than a program)

Øa×J

A niladic link that returns a list of strings, the lines
(to print it with the newlines as a full program just add Y back in).

Try it online! (the footer calls the link as a nilad (¢) and gets the Python representation of the result (ŒṘ) for clarity as the default full-program behaviour would smash the result together like abbccc...)

How?

Øa×J - main link: no arguments
Øa   - yield the alphabet = ['a','b','c',...,'z']
   J - range of length    = [1,2,3,...,26]
  ×  - multiplication     = ["a","bb","ccc",...,"zzzzzzzzzzzzzzzzzzzzzzzzzz"]
     - (Python multiplication lengthens chars to strings - not usually a Jelly thing)

Answer 17

MATL, 11 bytes

2Y2t!g*!YRc

Try it online!

Uses broadcast multiplication with ones to get a big square 26x26 matrix of the desired letters. Next, the lower triangular part is taken, and implicitly printed.

Also 11 bytes:

2Y2!t~!+YRc  % Using broadcast addition with zeroes
2Y2!l26X"YR  % Using 'repmat'

Answer 18

Javascript, 87 bytes, 72 bytes (A lot of thank to @steenbergh)

My first answer too:

for(i=1,j=97;j<123;){console.log(String.fromCharCode(j++).repeat(i++))};

Answer 19

Japt, 9 7 bytes

Outputs an array of lines

;C¬Ëp°E

Try it

---

Explanation

Split (¬) the lowercase alphabet (;C) to an array of characters, map over the array (Ë) and repeat (p) the current element by the current index (E) incremented (°) times.

Answer 20

Acc!!, 66 64 bytes

Count i while 27-i {
Count j while i-j {
Write 96+i
}
Write 10
}

Outputs with a leading and trailing newline. Try it online!

With comments

# Loop i from 0 to 26
Count i while 27-i {
    # Loop j from 0 to i (exclusive)
    Count j while i-j {
        # Print the i'th letter (1-indexed)
        Write 96+i
    }
    # Print a newline
    Write 10
}

Answer 21

Pip, 9 bytes

FczPcX++i

Try it online!

In pseudocode, this is

For-each c in z
    Print (c string-multiply ++i)

where z is preset to the lowercase alphabet and i is preset to 0.

---

Map-based solutions take one extra byte because they need the -n flag to display on multiple lines:

{aX++i}Mz
B X_+1MEz

Answer 22

R, 38 bytes

A relatively uninteresting answer. Iterate for i from 1 to 26, print the ith letter of the alphabet i times (with an implicit line break).

for(i in 1:26)print(rep(letters[i],i))

Try it online!

A more interesting approach might be to use something like the following:

cat(letters[(1:351*2)^.5+.5])

This gives us all the letters in the right amount, but no linebreaks. Perhaps someone smarter than me can figure out a way to use that to make a golfier answer.

Answer 23

Perl 5, 19 bytes

say$_ x++$"for a..z

Try it online!

Answer 24

Rust, 82 bytes

||for i in 1..27u8{println!("{}",((i+96) as char).to_string().repeat(i as usize))}

I had hoped that it would've been a lot shorter, but explicitly converting/casting between types takes a lot of bytes :(

Try it online!

Answer 25

PHP, 47 46 bytes

for($c=a;$i<26;)echo"
",str_pad($c,++$i,$c++);

or

for($c=a;$i<26;)echo str_pad("
",++$i+1,$c++);

Run with -nr or try it online.

Answer 26

J, 18 17 bytes

a.{~(#"0+&96)i.27

Explanation:

              i.27      - list of integers 0 - 26
     (   +&96)          - adds 96 to the above list (starting offset of 'a')
      #"0               - copies the right argument left argument times  
  {~                    - select items from a list (arguments reversed)
a.                      - the whole alphabet


#"0 +&96 is a hook, which means that at first +96 is applied to the list i.27,
resulting in a list 96, 97, 98... 122, then #"0 is applied to this result. 
So it is evaluated as ((i.27)#"0(96+i.27)){a:

Try it online!

Answer 27

Perl 6,  24  23 bytes

.say for 'a'..'z'Zx 1..*

Try it

.say for 'a'..*Zx 1..26

Try it

Answer 28

Octave, 25 24 bytes

['',tril((x=65:90)'+~x)]

Try it online!

Saved one byte thanks to Giuseppe who informed me that OP allows upper case letters.

Explanation:

Create a vector x with the ASCII-values of the upper case alphabet, and transpose it. Add the negated x (thus 26 zeros, in a row vector, in order to create a grid with (the ASCII-values of):

AAAA
BBBB
CCCC

Take the lower triangular matrix and convert to characters by concatenating with the empty string.

Answer 29

C (gcc), 48 bytes 50 bytes

Re-runnable version, as per cleblanc and Steadybox in the comments below.

s[9];main(i){for(;i<27;)puts(memset(s,i+95,i++));}

Try it online!

Answer 30

Japt, 17 16 11 bytes

_{-5 bytes thanks to Oliver}

In ISO-8859-1

;26ÆCgX pXÄ

Not the best score, but I'm still a novice. Any suggestions are very welcome.

Outputs list of lines, as OP allowed. Link contains 3 bytes more for newlines.

Try it online!

;                      - Use string variables
 26                    - Literal 26
   Æ                   - For range 0..26
    C                  - Alphabet
     gX                -         . character at index X
        pXÄ            - Duplicate X+1 times
                       - End function (implicit)