path: root/challenge-065/richard-park/apl/DigitsSum.aplf

 DigitsSum←{
⍝ ⍺: Number of digits 
⍝ ⍵: Sum of digits 
⍝ ←: Numbers with ⍺ digits whose digits sum to ⍵
     n←,1↓(⎕D∘.,⊢)⍣(¯1+⍺)⊢⎕D   ⍝ All numbers with ⍺ digits
     s←+/¨⍎¨¨n                 ⍝ Sum of digits
     (s=⍵)/⍎¨n                 ⍝ ←
 }