Solve 36, 37, 45, 53 in rust

rust/src/include/factors.rs

@@ -17,7 +17,7 @@ pub struct ProperDivisors<I>
     next_size: usize,
 }
 
-pub fn proper_divisors<I>(num: I) -> ProperDivisors<I>
+pub fn proper_divisors<I>(num: I) -> impl Iterator<Item = I>
 where I: Hash + Zero + One + Add + Ord + Copy + Div<Output=I> + Rem<Output=I> + 'static
 {
     return ProperDivisors::<I>::new(num);
@@ -48,9 +48,9 @@ where I: Hash + Zero + One + Add + Ord + Copy + Div<Output=I> + Rem<Output=I> +
                 return None;
             }
             if self.next_size == 0 {
-self.next_size += 1;
-return Some(one());
-}
+                self.next_size += 1;
+                return Some(one());
+            }
             while self.curr_index < self.current_batch.len() {
                 let result = self.current_batch[self.curr_index];
                 self.curr_index += 1;

rust/src/include/fibonacci.rs

@@ -0,0 +1,81 @@
+use std::ops::{Add,Mul};
+
+use num_traits::{one,zero,One,Zero};
+
+use crate::include::iter_cache::cache_iterator;
+
+pub fn fib<I>() -> impl Iterator<Item = I> where I: Copy + Zero + One + Add {
+    return cache_iterator(Fibonacci::<I>::new());
+}
+
+pub fn fib_by_3<I>() -> impl Iterator<Item = I> where I: Copy + Zero + One + Add + Mul {
+    return cache_iterator(FibonacciBy3::<I>::new());
+}
+
+pub struct Fibonacci<I> {
+    a: I,
+    b: I,
+}
+
+impl<I> Default for Fibonacci<I> where I: Zero + One {
+    fn default() -> Self {
+        return Fibonacci::<I>{
+            a: zero(),
+            b: one(),
+        };
+    }
+}
+
+impl<I> Fibonacci<I> where I: Zero + One {
+    pub fn new() -> Self {
+        return Default::default();
+    }
+}
+
+impl<I> Iterator for Fibonacci<I> where I: Zero + One + Add + Copy {
+    type Item = I;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let prior_a = self.a;
+        let prior_b = self.b;
+        self.b = self.a + self.b;
+        self.a = prior_b;
+        return Some(prior_a);
+    }
+}
+
+pub struct FibonacciBy3<I> {
+    a: I,
+    b: I,
+}
+
+impl<I> Default for FibonacciBy3<I> where I: Zero + One {
+    fn default() -> Self {
+        let two = one() + one();
+        let four = two + two;
+        return FibonacciBy3::<I>{
+            a: two,
+            b: four + four,
+        };
+    }
+}
+
+impl<I> FibonacciBy3<I> where I: Zero + One + Add {
+    pub fn new() -> Self {
+        return Default::default();
+    }
+}
+
+impl<I> Iterator for FibonacciBy3<I> where I: Zero + One + Add + Mul + Copy {
+    type Item = I;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let two = one() + one();
+        let four = two + two;
+        let prior_a = self.a;
+        let prior_b = self.b;
+        self.b = four * self.a + self.b;
+        self.a = prior_b;
+        return Some(prior_a);
+    }
+}

rust/src/include/iter_cache.rs

@@ -6,6 +6,14 @@ use std::sync::Once;
 static INIT: Once = Once::new();
 static mut CACHE_MAP: Option<RwLock<HashMap<(TypeId, TypeId), Mutex<Vec<Box<dyn std::any::Any>>>>>> = None;
 
+pub fn cache_iterator<I, T>(iterator: T) -> impl Iterator<Item = I>
+where
+    I: Iterator<Item = T> + 'static,
+    T: Copy + 'static
+{
+    return CachingIterator::new(iterator);
+}
+
 pub struct CachingIterator<I, T>
 where
     I: Iterator<Item = T> + 'static,

rust/src/include/mod.rs

@@ -1,5 +1,6 @@
 pub mod iter_cache;
 pub mod factors;
+pub mod fibonacci;
 pub mod math;
 pub mod primes;
 pub mod problems;

rust/src/include/primes.rs

@@ -5,19 +5,15 @@ use std::ops::{Add,Div,Mul,Rem};
 
 use num_traits::{one,zero,One,Zero};
 
-use crate::include::iter_cache::CachingIterator;
+use crate::include::iter_cache::cache_iterator;
 
-pub struct Eratosthenes<I>
-where I: Hash
-{
+pub struct Eratosthenes<I> where I: Hash {
     sieve: HashMap<I, Vec<I>>,
     prime: I,
     candidate: I,
 }
 
-impl<I> Default for Eratosthenes<I>
-where I: Hash + One + Zero + Add
-{
+impl<I> Default for Eratosthenes<I> where I: Hash + One + Zero + Add {
     fn default() -> Self {
         return Eratosthenes::<I>{
             sieve: HashMap::new(),
@@ -27,17 +23,13 @@ where I: Hash + One + Zero + Add
     }
 }
 
-impl<I> Eratosthenes<I>
-where I: Hash + One + Zero + Add
-{
+impl<I> Eratosthenes<I> where I: Hash + One + Zero + Add {
     pub fn new() -> Eratosthenes<I> {
         return Default::default();
     }
 }
 
-impl<I> Iterator for Eratosthenes<I>
-where I: Hash + One + Zero + Add + Mul + Ord + Copy
-{
+impl<I> Iterator for Eratosthenes<I> where I: Hash + One + Zero + Add + Mul + Ord + Copy {
     type Item = I;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -68,25 +60,19 @@ where I: Hash + One + Zero + Add + Mul + Ord + Copy
     }
 }
 
-pub fn primes<I>() -> impl Iterator<Item = I>
-where I: Hash + One + Zero + Add + Mul + Ord + Copy + 'static
-{
-    return CachingIterator::new(Eratosthenes::new());
+pub fn primes<I>() -> impl Iterator<Item = I> where I: Hash + One + Zero + Add + Mul + Ord + Copy + 'static {
+    return cache_iterator(Eratosthenes::new());
 }
 
-pub fn primes_until<I>(x: I) -> impl Iterator<Item = I>
-where I: Hash + One + Zero + Add + Mul + Ord + Copy + 'static
-{
+pub fn primes_until<I>(x: I) -> impl Iterator<Item = I> where I: Hash + One + Zero + Add + Mul + Ord + Copy + 'static {
     return primes::<I>().take_while(move |n| *n < x);
 }
 
-pub struct PrimeFactors<I>
-{
+pub struct PrimeFactors<I> {
     number: I
 }
 
-impl<I> PrimeFactors<I>
-{
+impl<I> PrimeFactors<I> {
     pub fn new(x: I) -> PrimeFactors<I> {
         return PrimeFactors{
             number: x
@@ -113,7 +99,8 @@ where I: Hash + Zero + One + Add + Ord + Copy + Div<Output=I> + Rem<Output=I> +
     }
 }
 
-pub fn prime_factors<I>(x: I) -> PrimeFactors<I>
+pub fn prime_factors<I>(x: I) -> impl Iterator<Item = I>
+where I: Hash + Zero + One + Add + Ord + Copy + Div<Output=I> + Rem<Output=I> + 'static
 {
     return PrimeFactors::new(x);
 }

rust/src/include/problems.rs

@@ -6,6 +6,10 @@ use crate::p~N::p~N;
 });
 use crate::p0027::p0027;
 use crate::p0034::p0034;
+use crate::p0036::p0036;
+use crate::p0037::p0037;
+use crate::p0045::p0045;
+use crate::p0053::p0053;
 use crate::p0069::p0069;
 use crate::p0076::p0076;
 use crate::p0077::p0077;
@@ -44,6 +48,10 @@ pub fn get_problem<'b>(n: usize) -> Option<ProblemRef<'b>> {
         24 =>  Some(( &24, p0024, false)),
         27 =>  Some(( &27, p0027, true)),
         34 =>  Some(( &34, p0034, false)),
+        36 =>  Some(( &36, p0036, false)),
+        37 =>  Some(( &37, p0037, false)),
+        45 =>  Some(( &45, p0045, false)),
+        53 =>  Some(( &53, p0053, false)),
         69 =>  Some(( &69, p0069, false)),
         76 =>  Some(( &76, p0076, false)),
         77 =>  Some(( &77, p0077, false)),

rust/src/include/utils.rs

@@ -1,3 +1,5 @@
+use std::string::ToString;
+
 #[cfg(not(any(target_arch="wasm32", target_arch="wasm64")))]
 use std::fs::read_to_string;
 #[cfg(not(any(target_arch="wasm32", target_arch="wasm64")))]
@@ -53,4 +55,9 @@ pub fn get_answer(n: usize) -> Answer {
         }
     }
     panic!("Answer not found");
-}
+}
+
+pub fn is_palindrome<I>(x: I) -> bool where I: ToString {
+    let s = x.to_string();
+    return s == s.chars().rev().collect::<String>();
+}

rust/src/lib.rs

@@ -11,6 +11,10 @@ pub mod p~N;
 });
 pub mod p0027;
 pub mod p0034;
+pub mod p0036;
+pub mod p0037;
+pub mod p0045;
+pub mod p0053;
 pub mod p0069;
 pub mod p0076;
 pub mod p0077;

rust/src/main.rs

@@ -26,6 +26,10 @@ pub mod p~N;
 });
 pub mod p0027;
 pub mod p0034;
+pub mod p0036;
+pub mod p0037;
+pub mod p0045;
+pub mod p0053;
 pub mod p0069;
 pub mod p0076;
 pub mod p0077;
@@ -40,9 +44,9 @@ fn main() {
     for i in sieve {
         println!("{}", i);
     }
-for i in 4..100 {
-println!("{}: {:?}", i, factors::proper_divisors(i).collect::<Vec<u16>>());
-}
+    for i in 4..100 {
+        println!("{}: {:?}", i, factors::proper_divisors(i).collect::<Vec<u16>>());
+    }
     let supported = generate_supported_problems(false);
 
     for id in supported {
@@ -73,6 +77,10 @@ seq!(N in 01..=20 {
 #[case::problem_24(24)]
 #[case::problem_27(27)]
 #[case::problem_34(34)]
+#[case::problem_36(36)]
+#[case::problem_37(37)]
+#[case::problem_45(45)]
+#[case::problem_53(53)]
 #[case::problem_69(69)]
 #[case::problem_76(76)]
 #[case::problem_77(77)]
@@ -100,7 +108,6 @@ fn test_problem(#[case] id: usize) -> Result<(), String> {
 }
 });
 
-
 #[cfg(test)]
 #[test]
 fn test_primes() -> Result<(), String> {
@@ -128,3 +135,18 @@ fn test_prime_factors() -> Result<(), String> {
     }
     Ok(())
 }
+
+#[cfg(test)]
+#[test]
+fn test_proper_divisors() -> Result<(), String> {
+    for i in 4..1024 {
+        let divisors = factors::proper_divisors(i).collect::<Vec<u16>>();
+        for &factor in divisors.iter() {
+            if factor == 1 {
+                continue;
+            }
+            assert!(divisors.iter().any(|&x| x * factor == i));
+        }
+    }
+    Ok(())
+}

rust/src/p0002.rs

@@ -14,17 +14,9 @@ terms. By starting with 1 and 2, the first 10 terms will be:
 By considering the terms in the Fibonacci sequence whose values do not exceed
 four million, find the sum of the even-valued terms.
 */
+use crate::include::fibonacci::fib_by_3;
 use crate::include::utils::Answer;
 
 pub fn p0002() -> Answer {
-    let mut answer: u64 = 0;
-    let mut i = 2;
-    let mut j = 8;
-    while i < 4000000 {
-        answer += i;
-        let tmp = 4 * j + i;
-        i = j;
-        j = tmp;
-    }
-    return Answer::Int(answer.into());
+    return Answer::Int(fib_by_3().take_while(|&x| x < 4000000).sum::<u64>().into());
 }

rust/src/p0004.rs

@@ -14,12 +14,7 @@ Find the largest palindrome made from the product of two 3-digit numbers.
 */
 use itertools::Itertools;
 
-use crate::include::utils::Answer;
-
-fn is_palindrome(x: u32) -> bool {
-    let s = x.to_string();
-    return s == s.chars().rev().collect::<String>();
-}
+use crate::include::utils::{is_palindrome,Answer};
 
 pub fn p0004() -> Answer {
     let mut answer: u32 = 0;

rust/src/p0036.rs

@@ -0,0 +1,26 @@
+/*
+Project Euler Problem 36
+
+Rust implementing a `reverse_bits()` function made this much more pleasant than expected
+
+Problem:
+
+The decimal number, 585 = 10010010012 (binary), is palindromic in both bases.
+
+Find the sum of all numbers, less than one million, which are palindromic in
+base 10 and base 2.
+
+(Please note that the palindromic number, in either base, may not include
+leading zeros.)
+*/
+use crate::include::utils::{is_palindrome,Answer};
+
+pub fn p0036() -> Answer {
+    let mut answer: u64 = 0;
+    for x in 1..1000000 {
+        if x == x.reverse_bits::<u64>() && is_palindrome(x) {
+            answer += x;
+        }
+    }
+    return Answer::Int(answer.into());
+}