Reduce allocations and refactoring

src/Julia/Problems001-050/Problem017.jl

@@ -1,4 +1,4 @@
-#= 
+#=
 Created on 28 Jul 2021
 
 @author: David Doblas Jiménez
@@ -9,39 +9,32 @@ https://projecteuler.net/problem=17 =#
 
 using BenchmarkTools
 
-function num2letters(num)
-    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"
-    )
-
+function num2letters(num, nums)
     if num <= 20
-        return length(nums[num])
+        return nums[num]
     elseif num < 100
         tens, units = divrem(num, 10)
-        return (length(nums[Int(tens) * 10]) + num2letters(units))
+        return (nums[tens*10] + num2letters(units, nums))
     elseif num < 1000
         hundreds, rest = divrem(num, 100)
         if rest != 0
-            return (num2letters(hundreds) + length(nums[100])
-            + length("and") + num2letters(rest))
+            return (
+                num2letters(hundreds, nums) +
+                nums[100] +
+                length("and") +
+                num2letters(rest, nums)
+            )
         else
-            return (num2letters(hundreds) + length(nums[100]))
+            return (num2letters(hundreds, nums) + nums[100])
         end
     else
         thousands, rest = divrem(num, 1000)
-        return (num2letters(thousands) + length(nums[1000]))
+        return (num2letters(thousands, nums) + nums[1000])
     end
 end
 
-
 function Problem17()
-    #= 
+    #=
     If the numbers 1 to 5 are written out in words: one, two, three, four,
     five, then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.
 
@@ -53,11 +46,44 @@ function Problem17()
     20 letters. The use of "and" when writing out numbers is in compliance
     with British usage. =#
 
+    nums = Dict(
+            0 => 0,
+            1 => 3,
+            2 => 3,
+            3 => 5,
+            4 => 4,
+            5 => 4,
+            6 => 3,
+            7 => 5,
+            8 => 5,
+            9 => 4,
+            10 => 3,
+            11 => 6,
+            12 => 6,
+            13 => 8,
+            14 => 8,
+            15 => 7,
+            16 => 7,
+            17 => 9,
+            18 => 8,
+            19 => 8,
+            20 => 6,
+            30 => 6,
+            40 => 5,
+            50 => 5,
+            60 => 5,
+            70 => 7,
+            80 => 6,
+            90 => 6,
+            100 => 7,
+            1000 => 8,
+    )
     n = 1000
     letters = 0
-    for num in 1:n
-        letters += num2letters(num)
+    for num = 1:n
+        letters += num2letters(num, nums)
     end
+
     return letters
 end