1 files changed, 42 insertions, 0 deletions
diff --git a/exercises/18_iterators/iterators4.rs b/exercises/18_iterators/iterators4.rs
new file mode 100644
index 0000000..79e1692
--- /dev/null
+++ b/exercises/18_iterators/iterators4.rs
@@ -0,0 +1,42 @@
+// iterators4.rs
+//
+// Execute `rustlings hint iterators4` or use the `hint` watch subcommand for a
+// hint.
+
+// I AM NOT DONE
+
+pub fn factorial(num: u64) -> u64 {
+    // Complete this function to return the factorial of num
+    // Do not use:
+    // - return
+    // Try not to use:
+    // - imperative style loops (for, while)
+    // - additional variables
+    // For an extra challenge, don't use:
+    // - recursion
+    // Execute `rustlings hint iterators4` for hints.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn factorial_of_0() {
+        assert_eq!(1, factorial(0));
+    }
+
+    #[test]
+    fn factorial_of_1() {
+        assert_eq!(1, factorial(1));
+    }
+    #[test]
+    fn factorial_of_2() {
+        assert_eq!(2, factorial(2));
+    }
+
+    #[test]
+    fn factorial_of_4() {
+        assert_eq!(24, factorial(4));
+    }
+}