Letter: More Solutions

from Gianluigi Quario (giangiquario@hotmail.com)

1. How many elements does a given variable have?

Restriction: assume that the keyboard does not have the comma (,) symbol.

CE←×/∘⍴ ⍝ ⍵←A

2. Is a value within a given range?

Restriction: assume that the keyboard does not have any relational operators.

C2←{+/×⍵[⍋⍵]-⍺} ⍝ ⍺←D0 ⍵←D1 ⍴⍵←→2

3. Sort a numeric array of integers in ascending order of the number of digits.

Restriction: assume that the keyboard does not have the format (⍕) or quad (⎕) symbol.

SN←{⍵[⍋⌈10⍟|(⍵+2×0=⍵)+×⍵;]} ⍝ ⍵←I2 (1↓⍴⍵)←→1

4. Return the element(s) of a numeric array indexed by its first dimension.

Restriction: assume that the keyboard does not have the shape of (⍴) symbol.

NB.(GQR) the definition of this problem is not complete:

a) should return an array with a lesser rank?

b) a scalar has not a “first dimension”, but it is required by the challenge:

  LD 6←→6

  LD←{,[1,(0<≡+/~0×⍵)/2]1↑[1],[(0<≡⍵)/1]⊂[⍬]⊖⍵}
       ⍝ ⍵←D (also scalar)

or

  LD_←{,[1,(0<≡+/~0×⍵)/2]1↑[1]⊖⍉1↓[1],[1 2]⍉,[⍬]0,⍵}
       ⍝ ⍵←D (also scalar)

or

  LD__←{1↑[1]⊖⍵} ⍝ ⍵←D ; ⍵ not scalar;
         NB.result has same rank of ⍵

5. Return the sum of element(s) of a numeric array on its first dimension.

Restriction: assume that the keyboard does not have the plus (+) symbol.

NB.(GQR) a scalar has not a “first dimension”, but it is required by the challenge:

  LS 6←→6

  LS←{⎕ML←2 ⋄ ↑¨⍴¨∊¨⊂[(~0∊⍴⍴⍵)/1]⍵⍴¨1}
          ⍝APL2 ⍝⍵←D (also scalar)

6. Convert the string representation of integers to numbers.

Restriction: assume that the keyboard does not have the execute (⍎) symbol.

  CN←{10⊥2⊥4↓[⎕IO]⍉11 ⎕DR,[⍬]⍵} ⍝ ⍵←C1 (also scalar)

  CN_←{10⊥2⊥¨4↓¨11 ⎕DR¨⍵} ⍝ ⍵←C1 (also scalar)

  CN__←{10⊥(-⎕AV⍳'0')+⎕AV⍳⍵} ⍝ ⍵←C1 (also scalar)

  CN___←{10⊥(-⎕IO)+'0123456789'⍳⍵} ⍝ ⍵←C1 (also scalar)

7. Return a numeric array as zeros, increasing the last dimension by 1.

Restriction: assume that the keyboard does not have the times (×), take (?), minus (-), or comma (,) symbols and it does not end with ⍴0.

ZM←{((((¯1+⍴⍴⍵)⍴0),1)+⍴⍵)⍴⍵=⍵+1} ⍝ ⍵←D

8. Return the first ones from a Boolean vector.

Restriction: assume that the keyboard does not have the not (~) or rotate (²) symbols.

FO←{⍵^1,(1↓⍵)≠¯1↓⍵} ⍝ ⍵←B1

9. Return the last ones from a Boolean vector.

Restriction: assume that the keyboard does not have the not (~) or rotate (²) symbols.

LO←{⍵^((1↓⍵)≠¯1↓⍵),1} ⍝ ⍵←B1

10. Return the elements of a numeric array found at given coordinates.

Restrictions: assume that a looping solution is not allowed nor one involving semi-colon and that index origin is 1.

RE← {(,⍺)[1+(⍴⍺)⊥⍉⍵-1]} ⍝ ⍺←D2 ; ⍵←D 1