add 92

src/euler92/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "euler92"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[profile.release]
+lto = "fat"

src/euler92/src/main.rs

@@ -0,0 +1,38 @@
+const MAXIMUM: usize = 10_000_000;
+
+fn main() {
+    let mut arrives_at_89 = 0;
+
+    for i in 1..MAXIMUM {
+        let mut number = i;
+        loop {
+            let sum: usize = number
+                .to_digits()
+                .into_iter()
+                .map(|d| d.pow(2) as usize)
+                .sum();
+            if sum == 89 {
+                arrives_at_89 += 1;
+                break;
+            } else if sum == 1 {
+                break;
+            }
+            number = sum;
+        }
+    }
+
+    println!("{arrives_at_89}");
+}
+
+trait ToDigits {
+    fn to_digits(&self) -> Vec<u8>;
+}
+
+impl ToDigits for usize {
+    fn to_digits(&self) -> Vec<u8> {
+        self.to_string()
+            .chars()
+            .map(|c| c.to_digit(10).unwrap() as _)
+            .collect()
+    }
+}