Improve performance

src/Julia/Problem014.jl

@@ -8,18 +8,10 @@ Solution for Problem 14 of Project Euler
 https://projecteuler.net/problem=14
 =#
 
-function chain_length(n, terms)
+function chain_length(n)#, terms)
     length = 0
-    while n != 1
-        if haskey(terms, n)
-            length += terms[n]
-            break
-        end
-        if n % 2 == 0
-            n = n ÷ 2
-        else
-            n = 3n + 1
-        end
+    while n > 1
+        n = iseven(n) ? n >> 1 : 3n + 1
         length += 1
     end
     return length
@@ -50,12 +42,10 @@ function Problem14()
     ans = 0
     limit = 1_000_000
     score = 0
-    terms = Dict{Int, Int}()
-    sizehint!(terms, limit)
-    for i in 1:limit
-        terms[i] = chain_length(i, terms)
-        if terms[i] > score
-            score = terms[i]
+    for i in 1:2:limit  # no need to check even numbers
+        longest = chain_length(i)
+        if longest > score
+            score = longest
             ans = i
         end
     end