From b8040027c95b094e94b768adcbd271acea622139 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Sommer?= <joerg@alea.gnuu.de>
Date: Thu, 30 Mar 2017 20:33:16 +0200
Subject: [PATCH] =?UTF-8?q?J=C3=B6rgs=20L=C3=B6sung=20f=C3=BCr=20Euler=208?=
 =?UTF-8?q?7=20in=20Rust?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 2017-03-28/Makefile         |  5 ++-
 2017-03-28/jo-so_euler87.rs | 62 +++++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+), 1 deletion(-)
 create mode 100644 2017-03-28/jo-so_euler87.rs

diff --git a/2017-03-28/Makefile b/2017-03-28/Makefile
index 968aae5..db17310 100644
--- a/2017-03-28/Makefile
+++ b/2017-03-28/Makefile
@@ -8,6 +8,9 @@ LDFLAGS=-lm
 
 .PHONY: all
 
-all: jo-so_euler87
+all: jo-so_euler87 jo-so_euler87_rust
 
 jo-so_euler87:
+
+jo-so_euler87_rust: jo-so_euler87.rs
+	rustc -O -g -o $@ $<
diff --git a/2017-03-28/jo-so_euler87.rs b/2017-03-28/jo-so_euler87.rs
new file mode 100644
index 0000000..c5611e1
--- /dev/null
+++ b/2017-03-28/jo-so_euler87.rs
@@ -0,0 +1,62 @@
+/*
+  Copyright © 2017 Jörg Sommer <joerg@alea.gnuu.de>
+
+  License: MIT https://opensource.org/licenses/MIT
+ */
+
+//////
+//
+// Solution of Euler 87 https://projecteuler.net/problem=87
+//
+fn gen_prime_numbers(limit: u32) -> Vec<u32> {
+    let mut ret = vec![2, 3];
+
+    let mut num = *ret.last().unwrap();
+    'num: while num + 2 <= limit {
+        num += 2;
+        for i in 3..((num as f32).sqrt() as u32 + 1) {
+            if num % i == 0 {
+                continue 'num;
+            }
+        }
+        ret.push(num);
+    }
+
+    ret
+}
+
+fn main() {
+    const LIMIT: u32 = 50_000_000;
+
+    // println!("pn {:?}", gen_prime_numbers(500));
+    let pn = gen_prime_numbers((LIMIT as f32).sqrt() as u32);
+
+    println!("There are {} numbers below sqrt(50.000.000)", pn.len());
+
+    let mut nums = Vec::new();
+
+    for pn2 in pn.iter() {
+        let pow2 = pn2.pow(2);
+
+        for pn3 in pn.iter() {
+            let sum = pow2 + pn3.pow(3);
+            if sum >= LIMIT {
+                break;
+            }
+
+            for pn4 in pn.iter() {
+                let sum2 = sum + pn4.pow(4);
+                if sum2 >= LIMIT {
+                    break;
+                }
+
+                nums.push(sum2);
+            }
+        }
+    }
+
+    nums.sort();
+    nums.dedup();
+
+    println!("Answer {}", nums.len());
+}