armstrong numbers

rust/armstrong-numbers/src/lib.rs

@@ -0,0 +1,12 @@
+pub fn is_armstrong_number(num: u32) -> bool {
+    if 0 == num {
+        return true;
+    }
+    let count = (num as f64).log10().floor() as u32 + 1;
+
+    let sum: u32 = (1..=count)
+        .map(|i| num % 10_u32.pow(i) / 10_u32.pow(i - 1))
+        .map(|x| (x).pow(count))
+        .sum();
+    sum == num
+}