September Morn Update

Task/Modular-inverse/Rust/modular-inverse-2.rust

@@ -0,0 +1,19 @@
+fn modinv(a0: isize, m0: isize) -> isize {
+    if m0 == 1 { return 1 }
+
+    let (mut a, mut m, mut x0, mut inv) = (a0, m0, 0, 1);
+
+    while a > 1 {
+        inv -= (a / m) * x0;
+        a = a % m;
+        std::mem::swap(&mut a, &mut m);
+        std::mem::swap(&mut x0, &mut inv);
+    }
+
+    if inv < 0 { inv += m0 }
+    inv
+}
+
+fn main() {
+  println!("{}", modinv(42, 2017))
+}