Print this diamond

Question

This question has been spreading like a virus in my office. There are quite a variety of approaches:

Print the following:

        1
       121
      12321
     1234321
    123454321
   12345654321
  1234567654321
 123456787654321
12345678987654321
 123456787654321
  1234567654321
   12345654321
    123454321
     1234321
      12321
       121
        1

Answer 1

APL (33 31)

A⍪1↓⊖A←A,0 1↓⌽A←⌽↑⌽¨⍴∘(1↓⎕D)¨⍳9

If spaces separating the numbers are allowed (as in the Mathematica entry), it can be shortened to 28 26:

A⍪1↓⊖A←A,0 1↓⌽A←⌽↑⌽∘⍕∘⍳¨⍳9

Explanation:

• (Long program:)
• ⍳9: a list of the numbers 1 to 9
• 1↓⎕D: ⎕D is the string '0123456789', 1↓ removes the first element
• ⍴∘(1↓⎕D)¨⍳9: for each element N of ⍳9, take the first N elements from 1↓⎕D. This gives a list: ["1", "12", "123", ... "123456789"] as strings

• ⌽¨: reverse each element of this list. ["1", "21", "321"...]

• (Short program:)

• ⍳¨⍳9: the list of 1 to N, for N [1..9]. This gives a list [[1], [1,2], [1,2,3] ... [1,2,3,4,5,6,7,8,9]] as numbers.
• ⌽∘⍕∘: the reverse of string representation of each of these lists. ["1", "2 1"...]
• (The same from now on:)
• A←⌽↑: makes a matrix from the list of lists, padding on the right with spaces, and then reverse that. This gives the upper quadrant of the diamond. It is stored in A.
• A←A,0 1↑⌽A: A, with the reverse of A minus its first column attached to the right. This gives the upper half of the rectangle. This is then stored in A again.
• A⍪1↓⊖A: ⊖A is A mirrored vertically (giving the lower half), 1↓ removes the top row of the lower half and A⍪ is the upper half on top of 1↓⊖A.

Answer 2

Mathematica 83 49 43

Sum[DiamondMatrix[k, 17], {k, 0, 8}] /. 0 -> "" // Grid

---

Analysis

The principle part of the code, Sum[DiamondMatrix[k, 17], {k, 0, 8}], can be checked on WolframAlpha.

The following shows the underlying logic of the approach, on a smaller scale.

a = 0~DiamondMatrix~5;
b = 1~DiamondMatrix~5;
c = 2~DiamondMatrix~5;
d = a + b + c;
e = d /. 0 -> "";
Grid /@ {a, b, c, d, e}

Answer 3

Python 72 69 67 61

Not clever:

s=str(111111111**2)
for i in map(int,s):print'%8s'%s[:i-1]+s[-i:]

Answer 4

GolfScript, 33 31 30 characters

Another GolfScript solution

17,{8-abs." "*10@-,1>.-1%1>n}%

Thank you to @PeterTaylor for another char.

Previos versions:

17,{8-abs" "*9,{)+}/9<.-1%1>+}%n*

(run online)

17,{8-abs" "*9,{)+}/9<.-1%1>n}%

Answer 5

PHP, 92 90 characters

<?for($a=-8;$a<9;$a++){for($b=-8;$b<9;){$c=abs($a)+abs($b++);echo$c>8?" ":9-$c;}echo"\n";}

Calculates and prints the Manhattan distance of the position from the centre. Prints a space if it's less than 1.

An anonymous user suggested the following improvement (84 characters):

<?for($a=-8;$a<9;$a++,print~õ)for($b=-8;$b<9;print$c>8?~ß:9-$c)$c=abs($a)+abs($b++);

Answer 6

Python, 60 59

for n in`111111111**2`:print`int('1'*int(n))**2`.center(17)

Abuses backticks and repunits.

Answer 7

C, 79 chars

v;main(i){for(;i<307;putchar(i++%18?v>8?32:57-v:10))v=abs(i%18-9)+abs(i/18-8);}

Answer 8

Mathematica 55 50 45 41

Grid[(10^Array[{9}-Abs[#-9]&,17]-1)^2/81]

Answer 9

GolfScript, 36 chars

Assuming that this is meant as a code-golf challenge, here's a basic GolfScript solution:

9,.);\-1%+:a{a{1$+7-.0>\" "if}%\;n}%

Answer 10

Ruby, 76 characters

def f(a)a+a.reverse[1..-1]end;puts f [*1..9].map{|i|f([*1..i]*'').center 17}

Improvements welcome. :)

Answer 11

k (64 50 chars)

-1'(::;1_|:)@\:((|!9)#'" "),'$i*i:"J"$(1+!9)#'"1";

Old method:

-1',/(::;1_|:)@\:((|!9)#\:" "),',/'+(::;1_'|:')@\:i#\:,/$i:1+!9;

Answer 12

Javascript, 114

My first entry on Codegolf!

for(l=n=1;l<18;n-=2*(++l>9)-1,console.log(s+z)){for(x=n,s="";x<9;x++)z=s+=" ";for(x=v=1;x<2*n;v-=2*(++x>n)-1)s+=v}

If this can be shortened any further, please comment :)

Answer 13

JavaScript, 81

for(i=9;--i+9;console.log(s))for(j=9;j;s=j--^9?k>0?k+s+k:" "+s:k+"")k=i<0?j+i:j-i

Answer 14

Perl 56 54 characters

Added 1 char for the -p switch.

Uses squared repunits to generate the sequence.

s//12345678987654321/;s|(.)|$/.$"x(9-$1).(1x$1)**2|eg

Answer 15

Common Lisp, 113 characters

(defun x(n)(if(= n 0)1(+(expt 10 n)(x(1- n)))))(dotimes(n 17)(format t"~17:@<~d~>~%"(expt(x(- 8(abs(- n 8))))2)))

First I noticed that the elements of the diamond could be expressed like so:

  1   =   1 ^ 2
 121  =  11 ^ 2
12321 = 111 ^ 2

etc.

x recursively calculates the base (1, 11, 111, etc), which is squared, and then printed centered by format. To make the numbers go up to the highest term and back down again I used (- 8 (abs (- n 8))) to avoid a second loop

Answer 16

Javascript, 137

With recursion:

function p(l,n,s){for(i=l;i;s+=" ",i--);for(i=1;i<=n;s+=i++);for(i-=2;i>0;s+=i--);return(s+="\n")+(l?p(l-1,n+1,"")+s:"")}alert(p(8,1,""))

First time on CG :)

Or 118

If I can find a JS implementation that executes 111111111**2 with higher precision.
(Here: 12345678987654320).

a="1",o="\n";for(i=0;i<9;i++,o+="         ".substr(i)+a*a+"\n",a+="1");for(i=8;i;i--)o+=o.split("\n")[i]+"\n";alert(o)

Answer 17

R, 71 characters

For the records:

s=c(1:9,8:1);for(i in s)cat(rep(" ",9-i),s[0:i],s[(i-1):0],"\n",sep="")

Answer 18

Perl, 43+1

adding +1 for -E which is required for say

say$"x(9-$_).(1x$_)**2for 1..9,reverse 1..8

edit: shortened a bit

Answer 19

Python, 65

for i in map(int,str(int('1'*9)**2)):print' '*(9-i),int('1'*i)**2

Answer 20

Groovy 77 75

i=(-8..9);i.each{a->i.each{c=a.abs()+it.abs();print c>8?' ':9-c};println""}

old version:

(-8..9).each{a->(-8..9).each{c=a.abs()+it.abs();print c>8?' ':9-c};println""}

Answer 21

Perl 6, 42 41 chars

say " "x 9-$_,(1 x$_)**2 for 1..9,(8...1)

Hey, it's one two characters shorter compared to Perl 5 - Perl 6 needs more whitespace than Perl 5, but it's still shorter.

Answer 22

Scala - 86 characters

val a="543210/.-./012345";for(i<-a){for(j<-a;k=99-i-j)print(if(k<1)" "else k);println}

Answer 23

Javascript, 129* 126

for(i=1;i<18;i++){s="";a=Math.abs(9-i);for(j=0;j<a;j++)s+=" ";for(k=a+1;k<=9;k++)s+=k-a;for(l=8;l>a;l--)s+=l-a;console.log(s)}

Includes suggestion from Shmiddty in comments. Original preserved below:

for(i=1;i<18;i++){s="";a=Math.abs(9-i);for(j=0;j<a;j++){s+=" "}for(k=a+1;k<=9;k++){s+=k-a}for(l=8;l>a;l--){s+=l-a}console.log(s)}

I'm sure this could be condensed further, but darned if I know how. :P

Answer 24

C, 98 chars

l=9,n;p(i){for(i=18;i;putchar(i?n>l?48+n-l:32:10))n=9<--i?18-i:i;}
main(){p(l--);l&&p(main());l++;}

Answer 25

K, 59

-1'(-:'9+k,1_|k:!9)$,/'$b,1_||:'b:(-1_'a),'|:'a:1_1+!:'!10;

Answer 26

VBA, 197

for i=1 to 9:?string(27-i*3,32)l;:for j=1 to i:?j;:next:for j=i-1 to 1 step -1:?j;:next:?:next:for i=8 to 1 step -1:?string(27-i*3,32)l;:for j=1 to i:?j;:next:for j=i-1 to 1 step -1:?j;:next:?:next

if vba didn't automatically add a space for the + sign it doesn't print, perhaps I could avoid the 27-i*3 construct for making it look right

Answer 27

Java, 177 chars

public class A{public static void main(String[]v){
for(int a=-8,b,c;a<9;a++){
for(b=-8;b<9;){c=Math.abs(a)+Math.abs(b++);
System.out.print(c>8?" ":9-c);}System.out.println();}}}

correct formatting of this solution (352 chars):

public class A {
    public void main(String[] args) {
        for (int a = -8; a < 9; a++) {
            for (int b = -8; b < 9;) {
                int c = Math.abs(a) + Math.abs(b++);
                System.out.print(c > 8 ? " " : 9 - c);
            }
            System.out.println("");
        }
    }
}

Answer 28

Javascript - 118 chars

for(i=1,s=8,d=0;i>0;d?(i=(i-1)/10,s++):(i=i*10+1,s--)){for(d=d||i>11111111,p='',j=0;j++<=s;)p+=' ';console.log(p+i*i)}

Output:

         1
        121
       12321
      1234321
     123454321
    12345654321
   1234567654321
  123456787654321
 12345678987654320
  123456787654321
   1234567654321
    12345654321
     123454321
      1234321
       12321
        121
         1

Unfortunately, I'm also struggling with Javascripts precision problem with the last calculation of 111111111 * 111111111

Answer 29

Javascript 88

for(i=9,a=Math.abs;--i>-9;console.log(o))for(j=9,o='';j-->-9;)o+=(n=9-a(i)-a(j))>0?n:' '

Answer 30

GolfScript (27 chars)

17,{8-abs' '*1`9*1$,>~.*n}/

or

17,{8-abs' '*.1`9*+9<~.*n}/

Both work by building a suitable repunit as a string and then converting to int and squaring to get a Demlo number.