From 5470995dc2283b0d298666ccf43d3f21b61d4e49 Mon Sep 17 00:00:00 2001
From: "Dr. Matthias Ratajczak" <m.ratajczak@hzdr.de>
Date: Fri, 19 Aug 2022 16:29:40 +0200
Subject: [PATCH] finish 30

---
 src/euler30/Cargo.toml  |  8 ++++++++
 src/euler30/src/main.rs | 24 ++++++++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 src/euler30/Cargo.toml
 create mode 100644 src/euler30/src/main.rs

diff --git a/src/euler30/Cargo.toml b/src/euler30/Cargo.toml
new file mode 100644
index 0000000..1a85898
--- /dev/null
+++ b/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]
diff --git a/src/euler30/src/main.rs b/src/euler30/src/main.rs
new file mode 100644
index 0000000..b870432
--- /dev/null
+++ b/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)
+}