From e3c5151a8226546ff5c1f186a897f79de8f74eed Mon Sep 17 00:00:00 2001
From: "Dr. Matthias Ratajczak" <m.ratajczak@hzdr.de>
Date: Tue, 30 Aug 2022 17:40:04 +0200
Subject: [PATCH] 51: replace skip with skip_while

---
 lib/primes/src/lib.rs   | 15 +++++++--------
 src/euler51/src/main.rs |  2 +-
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/lib/primes/src/lib.rs b/lib/primes/src/lib.rs
index dd66f4b..3b2de7a 100644
--- a/lib/primes/src/lib.rs
+++ b/lib/primes/src/lib.rs
@@ -5,6 +5,7 @@ use std::fmt::Display;
 use std::fs::File;
 use std::hash::Hash;
 use std::io::Write;
+use std::slice::Iter;
 
 use num::FromPrimitive;
 use num::Num;
@@ -12,7 +13,7 @@ use num::ToPrimitive;
 
 #[derive(Clone)]
 pub struct Primes<T> {
-    pub vector: Vec<T>,
+    vector: Vec<T>,
     set: HashSet<T>,
 }
 
@@ -58,9 +59,7 @@ where
 
         let upper_limit = Self::calc_upper_limit(max_value);
         for i in 2..upper_limit {
-            let skip = Self::find_number_to_skip_until_min_value(min_value, i);
-
-            for multiple in (i * i..max_value).step_by(i).skip(skip) {
+            for multiple in (i * i..max_value).step_by(i).skip_while(|i| i < &min_value) {
                 let idx = multiple - min_value;
                 // SAFETY: `multiple` will always be between min_value and max_value
                 // (which define the length of the array), therfore idx is always smaller than the
@@ -76,10 +75,6 @@ where
         f64::sqrt(max_value as f64).ceil() as usize
     }
 
-    fn find_number_to_skip_until_min_value(min_value: usize, i: usize) -> usize {
-        ((min_value.saturating_sub(i * i)) as f64 / i as f64).ceil() as usize
-    }
-
     pub fn remove(&mut self, num: &T) {
         if let Some(index) = self.vector.iter().position(|x| x == num) {
             self.vector.remove(index);
@@ -107,6 +102,10 @@ where
             writeln!(f, "{p}").unwrap();
         }
     }
+
+    pub fn iter(&self) -> Iter<T> {
+        self.vector.iter()
+    }
 }
 
 #[cfg(test)]
diff --git a/src/euler51/src/main.rs b/src/euler51/src/main.rs
index 3d1c381..4b1c283 100644
--- a/src/euler51/src/main.rs
+++ b/src/euler51/src/main.rs
@@ -44,7 +44,7 @@ fn main() {
         MAX_PATTERN_LENGTH,
         AMOUNT_OF_DIGITS_IN_NUMBER,
     ) {
-        for prime in &all_primes.vector {
+        for prime in all_primes.iter() {
             primes_matching_pattern.clear();
 
             let digits = prime.to_digits();