2016 Update

Task/Fibonacci-sequence/Rust/fibonacci-sequence-2.rust

@@ -1,16 +1,12 @@
+use std::mem;
 fn main() {
-    fn fib(n: i32) -> i32 {
-        fn _fib(n: i32, a: i32, b: i32) -> i32 {
-            match (n, a, b) {
-                (0, _, _) => a,
-                _         => _fib(n-1, a+b, a)
-            }
-        }
+    fibonacci(0,1);
+}
 
-        _fib(n, 0, 1)
-    }
-
-    for n in 0..20 {
-        println!("{}", fib(n));
+fn fibonacci(mut prev: usize, mut curr: usize) {
+    mem::swap(&mut prev, &mut curr);
+    if let Some(n) = curr.checked_add(prev) {
+        println!("{}", n);
+        fibonacci(prev, n);
     }
 }