[gleam][prime-factors] use cons to add to list and reverse after

gleam/prime-factors/src/prime_factors.gleam

@@ -1,13 +1,13 @@
 import gleam/list
 
 pub fn factors(value: Int) -> List(Int) {
-  do_factors(value, 2, [])
+  list.reverse(factors_iter(value, 2, []))
 }
 
-fn do_factors(n: Int, i: Int, factors: List(Int)) -> List(Int) {
-  case i <= n, n % i == 0 {
-    False, _ -> factors
-    _, True -> do_factors(n / i, i, list.append(factors, [i]))
-    _, False -> do_factors(n, i + 1, factors)
+fn factors_iter(n: Int, i: Int, factors: List(Int)) -> List(Int) {
+  case n, n % i {
+    1, _ -> factors
+    _, 0 -> factors_iter(n / i, i, [i, ..factors])
+    _, _ -> factors_iter(n, i + 1, factors)
   }
 }