From 12ec3b5d1b4c12ed923abc9ad80e0522be828491 Mon Sep 17 00:00:00 2001
From: CORR1T <corsin@ragett.li>
Date: Mon, 7 Jun 2021 15:38:06 +0200
Subject: [PATCH] checks every second number

---
 primes/java/src/DefaultPrimes.java | 7 ++++---
 primes/rust/src/main.rs            | 8 +++++---
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/primes/java/src/DefaultPrimes.java b/primes/java/src/DefaultPrimes.java
index 9cb3cac..cf2021a 100644
--- a/primes/java/src/DefaultPrimes.java
+++ b/primes/java/src/DefaultPrimes.java
@@ -6,15 +6,16 @@ public class DefaultPrimes implements Primes {
     // (will make the code 15% slower)
     @SuppressWarnings("ForLoopReplaceableByForEach")
     public List<Integer> primes(int max) {
-        List<Integer> primesList = new ArrayList<>(10000);
+        List<Integer> primesList = new ArrayList<>(max);
 
         primesList.add(2);
 
-        for (int i = 3; i < max; i++) { //go through all numbers
+        for (int i = 3; i < max; i += 2) { //go through all numbers
             boolean isPrime = true;
+            double sqrRoot = Math.sqrt(i);
             for (int j = 0; j < primesList.size(); j++) { //test each number
                 int prime = primesList.get(j);
-                if (prime > Math.sqrt(i)) {
+                if (prime >= sqrRoot) {
                     break;
                 }
                 if (i % prime == 0) { //i = test number, j = some known prime
diff --git a/primes/rust/src/main.rs b/primes/rust/src/main.rs
index ee8b917..e376726 100644
--- a/primes/rust/src/main.rs
+++ b/primes/rust/src/main.rs
@@ -24,9 +24,10 @@ fn primes(max: u32) -> Vec<u32> {
 
     primes_list.push(2);
 
-    for i in 3..max { //go through all numbers
+    for mut i in 3..max {
+        let sqr_root: u32 = (i as f64).sqrt() as u32;
         for prime in &primes_list { //test each number
-            if *prime > (i as f64).sqrt() as u32 {
+            if *prime > sqr_root {
                 primes_list.push(i);
                 break;
             }
@@ -34,7 +35,8 @@ fn primes(max: u32) -> Vec<u32> {
                 break;
             }
         }
+        i += 1;
     }
 
-    return primes_list;
+    primes_list
 }
\ No newline at end of file