init

problems/p34/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "p34"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+rayon = "1.11.0"

problems/p34/src/main.rs

@@ -0,0 +1,30 @@
+use rayon::prelude::*;
+
+fn is_fact_sum(num: u32) -> bool {
+    let factorials = [1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880];
+    let mut digits = Vec::new();
+    let mut a = num % 10;
+    let mut b = num / 10;
+    digits.push(a);
+    while b != 0 {
+        a = b % 10;
+        b /= 10;
+        digits.push(a);
+    }
+    let fact_sum: u32 = digits.iter().map(|&x| factorials[x as usize]).sum();
+    fact_sum == num
+}
+#[test]
+fn test_is_fact_sum() {
+    assert!(is_fact_sum(145));
+    assert!(!is_fact_sum(146));
+}
+
+fn main() {
+    // 小于7位
+    let sum: u32 = (3..9999999)
+        .into_par_iter()
+        .filter(|&x| is_fact_sum(x))
+        .sum();
+    println!("{sum}");
+}