Solution 3

src/bin/problem_3.rs

@@ -0,0 +1,34 @@
+fn main() {
+    let result = prime_factors(600851475143).into_iter().max();
+    println!("Result: {}", result.unwrap());
+}
+
+fn prime_factors(number: i64) -> Vec<i64> {
+    let mut factors = vec![2];
+    let upper: i64 = (number as f64).sqrt().ceil() as i64;
+    for i in 3..upper {
+        let mut is_prime = true;
+        for factor in factors.clone() {
+            if i % factor == 0 {
+                is_prime = false;
+                break;
+            }
+        }
+        if is_prime && number % i == 0 {
+            factors.push(i);
+        }
+    }
+
+    return factors;
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::prime_factors;
+
+    #[test]
+    fn it_works() {
+        let result = prime_factors(13195).into_iter().max();
+        assert_eq!(result.unwrap(), 29);
+    }
+}