solved 50

src/bin/problem_50.rs

@@ -0,0 +1,37 @@
+fn main() {
+    println!("{}", solve())
+}
+
+fn solve() -> usize {
+    let mut primes = vec![];
+
+    for n in 2..=1000000 {
+        let prime_check_max = (n as f64).sqrt().ceil() as usize;
+        let mut is_prime = true;
+        for prime in primes.clone() {
+            if n % prime == 0 {
+                is_prime = false;
+                break;
+            } else if prime > prime_check_max {
+                break;
+            }
+        }
+        if is_prime {
+            primes.push(n);
+        }
+    }
+
+    let mut chain_length = primes.len() - 1;
+    loop {
+        for prime_window in primes.windows(chain_length) {
+            let sum = prime_window.iter().map(|&prime| prime).sum::<usize>();
+            if primes.contains(&sum) {
+                return sum
+            }
+            if sum > 1000000 {
+                break;
+            }
+        }
+        chain_length -= 1;
+    }
+}