Solve p27 in javascript, rust

README.rst

@@ -78,7 +78,7 @@ Olivia's Project Euler Solutions
 |            |                          |        | |CodeQL| |br|     |
 |            |                          |        | |Java-lint|       |
 +------------+--------------------------+--------+-------------------+
-| JavaScript | Node 12+ |br|            | 20     | |JavaScript| |br| |
+| JavaScript | Node 12+ |br|            | 21     | |JavaScript| |br| |
 |            | Bun 1.0+ |br|            |        | |Js-Cov| |br|     |
 |            | Firefox [2]_ |br|        |        | |CodeQL| |br|     |
 |            | Chrome [2]_              |        | |ESLint|          |
@@ -88,7 +88,7 @@ Olivia's Project Euler Solutions
 |            | GraalPy 23.1+ |br|       |        | |CodeQL| |br|     |
 |            | Pyodide 0.26.2+ [3]_     |        | |PythonLint|      |
 +------------+--------------------------+--------+-------------------+
-| Rust       | 1.69+                    | 27     | |Rust| |br|       |
+| Rust       | 1.69+                    | 28     | |Rust| |br|       |
 |            |                          |        | |Rs-Cov| |br|     |
 |            |                          |        | |RustClippy|      |
 +------------+--------------------------+--------+-------------------+

docs/index.rst

@@ -119,7 +119,7 @@ Problems Solved
 +-----------+------------+------------+------------+------------+------------+------------+------------+
 |:prob:`25` |            |            |            |            |            |:py-d:`0025`|            |
 +-----------+------------+------------+------------+------------+------------+------------+------------+
-|:prob:`27` |            |            |            |            |            |:py-d:`0027`|            |
+|:prob:`27` |            |            |            |            |:js-d:`0027`|:py-d:`0027`|:rs-d:`0027`|
 +-----------+------------+------------+------------+------------+------------+------------+------------+
 |:prob:`28` |            |            |            |            |            |:py-d:`0028`|            |
 +-----------+------------+------------+------------+------------+------------+------------+------------+

docs/javascript/p0027.rst

@@ -0,0 +1,18 @@
+JavaScript Implementation of Problem 27
+=======================================
+
+View source code :source:`javascript/src/p0027.js`
+
+Includes
+--------
+
+- `primes <./primes.html>`_
+
+Problem Solution
+----------------
+
+.. js:autofunction:: p0027
+
+.. literalinclude:: ../../javascript/src/p0027.js
+   :language: javascript
+   :linenos:

docs/javascript/primes.rst

@@ -9,6 +9,12 @@ View source code :source:`javascript/src/lib/primes.js`
 
 .. js:autofunction:: primes.primeFactors
 
+.. js:autofunction:: primes.primeAndNegatives
+
+.. js:autofunction:: primes.isComposite
+
+.. js:autofunction:: primes.isPrime
+
 .. literalinclude:: ../../javascript/src/lib/primes.js
    :language: javascript
    :linenos:

docs/rust/p0027.rst

@@ -0,0 +1,18 @@
+Rust Implementation of Problem 27
+=================================
+
+View source code :source:`rust/src/p0027.rs`
+
+Includes
+--------
+
+- `primes <./primes.html>`_
+
+Problem Solution
+----------------
+
+.. rust:fn:: p0027::p0027() -> utils::Answer
+
+.. literalinclude:: ../../rust/src/p0027.rs
+   :language: rust
+   :linenos:

javascript/README.rst

@@ -116,6 +116,7 @@ Problems Solved
 -  ☒ `17 <./src/p0017.js>`__
 -  ☒ `20 <./src/p0020.js>`__
 -  ☒ `22 <./src/p0022.js>`__
+-  ☒ `27 <./src/p0027.js>`__
 -  ☒ `34 <./src/p0034.js>`__
 -  ☒ `76 <./src/p0076.js>`__
 -  ☒ `836 <./src/p0836.js>`__

javascript/euler.test.js

@@ -36,6 +36,7 @@ const answers = {
     17: [require('./src/p0017.js'), false],
     20: [require('./src/p0020.js'), false],
     22: [require('./src/p0022.js'), false],
+    27: [require('./src/p0027.js'), false],
     34: [require('./src/p0034.js'), false],
     76: [require('./src/p0076.js'), true],
     836: [require('./src/p0836.js'), false],

javascript/src/lib/primes.js

@@ -128,3 +128,46 @@ function* primeFactors(num) {
     }
 }
 exports.primeFactors = primeFactors;
+
+/**
+ * Iterates over the prime numbers (and their negatives) up to an (optional) limit, with caching.
+ *
+ * This iterator leverages the :js:func:`primes.primes` iterator.
+ * @param {number | null} stop
+ * @yield {number}
+ */
+function* primesAndNegatives(stop = null) {
+    for (p of primes(stop)) {
+        yield p;
+        yield -p;
+    }
+}
+exports.primesAndNegatives = primesAndNegatives;
+
+/**
+ * Tests if a number is composite
+ * @param {number} n
+ * @return {number} 0 if prime, or the first prime factor if not
+ */
+function isComposite(n) {
+    const factors = primeFactors(n);
+    const first = factors.next().value;
+    if (factors.next().done) {
+        return 0;
+    }
+    return first;
+}
+exports.isComposite = isComposite;
+
+/**
+ * Tests if a number is prime
+ * @param {number} n
+ * @return {boolean}
+ */
+function isPrime(n) {
+    if (n < 2) {
+        return false;
+    }
+    return !isComposite(n);
+}
+exports.isPrime = isPrime;

javascript/src/p0027.js

@@ -0,0 +1,50 @@
+/**
+ * Project Euler Problem 27
+ *
+ * Another good problem for code golf
+ *
+ * Problem: Euler discovered the remarkable quadratic formula:
+ *
+ * n**2+n+41
+ *
+ * It turns out that the formula will produce 40 primes for the consecutive
+ * integer values 0≤n≤39. However, when ``n=40``, ``40**2+40+41=40(40+1)+41`` is divisible
+ * by 41, and certainly when ``n=41``, ``41**2+41+41`` is clearly divisible by 41.
+ *
+ * The incredible formula ``n**2−79n+1601`` was discovered, which produces 80 primes
+ * for the consecutive values 0≤n≤79. The product of the coefficients, −79 and
+ * 1601, is −126479.
+ *
+ * Considering quadratics of the form:
+ *
+ *     n**2+an+b
+ *
+ * , where ``|a|<1000`` and ``|b|≤1000``
+ *
+ * where ``|n|`` is the modulus/absolute value of n, e.g. ``|11|=11`` and ``|−4|=4``
+ *
+ * Find the product of the coefficients, a and b, for the quadratic expression
+ * that produces the maximum number of primes for consecutive values of n,
+ * starting with n=0.
+ *
+ * @return {number}
+ */
+exports.p0027 = function() {
+    let streak = 0;
+    let answer = 0;
+    for (let a = -999; a < 1000; a++) {
+        for (b of primes.primesAndNegatives(1001)) {
+            let i = 0;
+            while (primes.isPrime((i + a) * i + b)) {
+                i++;
+            }
+            if (i > streak) {
+                streak = i;
+                answer = a * b;
+            }
+        }
+    }
+    return answer;
+};
+
+const primes = require('./lib/primes.js');

rust/README.rst

@@ -79,6 +79,7 @@ Problems Solved
 -  ☒ `20 <./src/p0020.rs>`__
 -  ☒ `22 <./src/p0022.rs>`__
 -  ☒ `24 <./src/p0024.rs>`__
+-  ☒ `27 <./src/p0027.rs>`__
 -  ☒ `34 <./src/p0034.rs>`__
 -  ☒ `69 <./src/p0069.rs>`__
 -  ☒ `76 <./src/p0076.rs>`__

rust/src/include/primes.rs

@@ -165,5 +165,8 @@ where I: Hash + Zero + One + Add + Ord + Copy + Div<Output=I> + Rem<Output=I>
 pub fn is_prime<I>(x: I) -> bool
 where I: Hash + Zero + One + Add + Ord + Copy + Div<Output=I> + Rem<Output=I>
 {
+    if x < (one() + one()) {
+        return false;
+    }
     return is_composite(x) == zero();
 }

rust/src/main.rs

@@ -20,6 +20,7 @@ mod p~N;
 });
 mod p0022;
 mod p0024;
+mod p0027;
 mod p0034;
 mod p0069;
 mod p0076;
@@ -55,6 +56,7 @@ fn get_problem<'b>(n: usize) -> ProblemRef<'b> {
         20 =>  ( &20, p0020::p0020, false),
         22 =>  ( &22, p0022::p0022, false),
         24 =>  ( &24, p0024::p0024, false),
+        27 =>  ( &27, p0027::p0027, false),
         34 =>  ( &34, p0034::p0034, false),
         69 =>  ( &69, p0069::p0069, false),
         76 =>  ( &76, p0076::p0076, false),
@@ -75,6 +77,7 @@ fn main() {
     let mut answers: Vec<usize> = (1..=20).collect();
     answers.push(22);
     answers.push(24);
+    answers.push(27);
     answers.push(34);
     answers.push(69);
     answers.push(76);
@@ -102,6 +105,7 @@ seq!(N in 01..=20 {
 )*
 #[case::problem_22(22)]
 #[case::problem_24(24)]
+#[case::problem_27(27)]
 #[case::problem_34(34)]
 #[case::problem_69(69)]
 #[case::problem_76(76)]

rust/src/p0027.rs

@@ -0,0 +1,52 @@
+/*
+Project Euler Problem 27
+
+Another good problem for code golf
+
+Problem:Euler discovered the remarkable quadratic formula:
+
+n**2+n+41
+
+It turns out that the formula will produce 40 primes for the consecutive
+integer values 0≤n≤39. However, when ``n=40``, ``40**2+40+41=40(40+1)+41`` is divisible
+by 41, and certainly when ``n=41``, ``41**2+41+41`` is clearly divisible by 41.
+
+The incredible formula ``n**2−79n+1601`` was discovered, which produces 80 primes
+for the consecutive values 0≤n≤79. The product of the coefficients, −79 and
+1601, is −126479.
+
+Considering quadratics of the form:
+
+    n**2+an+b
+
+, where ``|a|<1000`` and ``|b|≤1000``
+
+where ``|n|`` is the modulus/absolute value of n, e.g. ``|11|=11`` and ``|−4|=4``
+
+Find the product of the coefficients, a and b, for the quadratic expression
+that produces the maximum number of primes for consecutive values of n,
+starting with n=0.
+*/
+use crate::primes::{is_prime,primes_until};
+use crate::include::utils::Answer;
+
+pub fn p0027() -> Answer {
+    let mut streak: i64 = 0;
+    let mut answer: i64 = 0;
+
+    for a in (-999)..1000 {
+        for b in primes_until::<i64>(1001) {
+            for &bp in &[b, -b] {
+                let mut i = 0;
+                while is_prime((i + a) * i + bp) {
+                    i += 1;
+                }
+                if i > streak {
+                    streak = i;
+                    answer = a * bp;
+                }
+            }
+        }
+    }
+    return Answer::Int(answer.into());
+}