From 287fd1d84a81371fb1ad64de2450762c98be7fc3 Mon Sep 17 00:00:00 2001
From: Jude Southworth <judesouthworth@pm.me>
Date: Fri, 2 Oct 2020 17:27:19 +0000
Subject: [PATCH] Create problem27.rs

---
 problem27.rs | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 problem27.rs

diff --git a/problem27.rs b/problem27.rs
new file mode 100644
index 0000000..f3efa9d
--- /dev/null
+++ b/problem27.rs
@@ -0,0 +1,67 @@
+#[derive(Debug)]
+struct MaxValues {
+    pub a: isize,
+    pub b: isize,
+    pub n: isize,
+}
+
+#[derive(Clone, Copy)]
+enum IsPrime {
+    Prime,
+    NotPrime,
+}
+
+impl IsPrime {
+    pub fn is_prime(&self) -> bool {
+        match self {
+            Self::Prime => true,
+
+            Self::NotPrime => false,
+        }
+    }
+}
+
+fn is_number_prime(i: isize, sieve: &Vec<IsPrime>) -> bool {
+    if i < 0 {
+        false
+    }
+    else {
+        sieve[i as usize].is_prime()
+    }
+}
+
+fn main() {
+    let mut sieve = vec![IsPrime::Prime; 1_000_000];
+
+    for i in 2..999_999_usize {
+        if is_number_prime(i as isize, &sieve) {
+            let mut i_m = i * 2;
+
+            while i_m <= 999_999 {
+                sieve[i_m] = IsPrime::NotPrime;
+
+                i_m += i;
+            }
+        }
+    }
+
+    let mut maxes = MaxValues { a: 0, b: 0, n: 0 };
+
+    for a in -999..999 {
+        for b in -1000..1000 {
+            let mut n: isize = 0;
+
+            while is_number_prime(n.pow(2) + a*n + b, &sieve) {
+                n += 1;
+            }
+
+            if n > maxes.n {
+                maxes.n = n;
+                maxes.a = a;
+                maxes.b = b;
+            }
+        }
+    }
+
+    println!("{:?}", maxes);
+}