Improve performance

src/Julia/Problem017.jl

@@ -8,32 +8,23 @@ Solution for Problem 17 of Project Euler
 https://projecteuler.net/problem=17
 =#
 
-function num2letters(num)
+function num2letters(num, dic)
-    nums = Dict(
-        0 => "", 1 => "one", 2 => "two", 3 => "three", 4 => "four", 5 => "five",
-        6 => "six", 7 => "seven", 8 => "eight", 9 => "nine", 10 => "ten",
-        11 => "eleven", 12 => "twelve", 13 => "thirteen", 14 => "fourteen",
-        15 => "fifteen", 16 => "sixteen", 17 => "seventeen", 18 => "eighteen",
-        19 => "nineteen", 20 => "twenty", 30 => "thirty", 40 => "forty",
-        50 => "fifty", 60 => "sixty", 70 => "seventy", 80 => "eighty",
-        90 => "ninety", 100 => "hundred", 1000 => "thousand"
-)
-
     if num <= 20
-        return length(nums[num])
+        return length(dic[num])
     elseif num < 100
         tens, units = divrem(num, 10)
-        return length(nums[tens * 10]) + num2letters(units)
+        return length(dic[tens * 10]) + num2letters(units, dic)
     elseif num < 1000
         hundreds, rest = divrem(num, 100)
         if rest != 0
-            return num2letters(hundreds) + length(nums[100]) + length("and") + num2letters(rest)
+            return num2letters(hundreds, dic) + length(dic[100])
+            + length("and") + num2letters(rest, dic)
         else
-            return num2letters(hundreds) + length(nums[100])
+            return num2letters(hundreds, dic) + length(dic[100])
         end
     else
         thousands, rest = divrem(num, 1000)
-        return num2letters(thousands) + length(nums[1000])
+        return num2letters(thousands, dic) + length(dic[1000])
     end
 end
 
@@ -50,10 +41,20 @@ function Problem17()
     20 letters. The use of "and" when writing out numbers is in compliance
     with British usage.
     =#
+    nums = Dict(
+        0 => "", 1 => "one", 2 => "two", 3 => "three", 4 => "four", 5 => "five",
+        6 => "six", 7 => "seven", 8 => "eight", 9 => "nine", 10 => "ten",
+        11 => "eleven", 12 => "twelve", 13 => "thirteen", 14 => "fourteen",
+        15 => "fifteen", 16 => "sixteen", 17 => "seventeen", 18 => "eighteen",
+        19 => "nineteen", 20 => "twenty", 30 => "thirty", 40 => "forty",
+        50 => "fifty", 60 => "sixty", 70 => "seventy", 80 => "eighty",
+        90 => "ninety", 100 => "hundred", 1000 => "thousand"
+    )
+
     n = 1000
     letters = 0
     for num in 1:n
-        letters += num2letters(num)
+        letters += num2letters(num, nums)
     end
     return letters
 end