finish 30

src/euler30/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "euler30"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/euler30/src/main.rs

@@ -0,0 +1,24 @@
+use std::collections::HashMap;
+
+fn main() {
+    let hm: HashMap<_, _> = (0..10_u64).into_iter().map(|d| (d, d.pow(5))).collect();
+
+    let result: Vec<_> = (2..=10_000_000)
+        .into_iter()
+        .filter(|n| is_valid(*n, &hm))
+        .collect();
+
+    println!("{}", result.iter().sum::<u64>());
+}
+
+fn sum_of_power_of_digits(x: u64, hm: &HashMap<u64, u64>) -> u64 {
+    x.to_string()
+        .chars()
+        .map(|c| c.to_digit(10).unwrap() as u64)
+        .map(|d| hm.get(&d).unwrap())
+        .sum()
+}
+
+fn is_valid(x: u64, hm: &HashMap<u64, u64>) -> bool {
+    x == sum_of_power_of_digits(x, hm)
+}