solve problems 6, 8, 9 in JavaScript

README.rst

@@ -35,7 +35,7 @@ LivInTheLookingGlass’s Project Euler solutions
 +------------+---------------------+--------+---------------+
 | C#         | .NET 2+             |  2     | |C#i|         |
 +------------+---------------------+--------+---------------+
-| JavaScript | Node 12+            |  2     | |JavaScript|  |
+| JavaScript | Node 12+            |  5     | |JavaScript|  |
 +------------+---------------------+--------+---------------+
 | Python     | CPython 3.6+ |br|   | 70     | |Python|      |
 |            | Pypy 3.6+ |br|      |        |               |

docs/index.rst

@@ -109,13 +109,13 @@ This project is divided into several Makefiles, connected by a root Makefile whi
 +-----------+------+------+------+------+------+
 |:prob:`5`  |  |d| |      |      |  |d| |  |d| |
 +-----------+------+------+------+------+------+
-|:prob:`6`  |  |d| |      |      |  |d| |  |d| |
+|:prob:`6`  |  |d| |      |  |d| |  |d| |  |d| |
 +-----------+------+------+------+------+------+
 |:prob:`7`  |  |d| |      |      |  |d| |  |d| |
 +-----------+------+------+------+------+------+
-|:prob:`8`  |  |d| |      |      |  |d| |  |d| |
+|:prob:`8`  |  |d| |      |  |d| |  |d| |  |d| |
 +-----------+------+------+------+------+------+
-|:prob:`9`  |  |d| |      |      |  |d| |  |d| |
+|:prob:`9`  |  |d| |      |  |d| |  |d| |  |d| |
 +-----------+------+------+------+------+------+
 |:prob:`10` |  |d| |      |      |  |d| |  |d| |
 +-----------+------+------+------+------+------+

docs/javascript/p0006.rst

@@ -0,0 +1,10 @@
+JavaScript Implementation of Problem 6
+======================================
+
+View source code `here on GitHub! <https://github.com/LivInTheLookingGlass/Euler/blob/master/javascript/p0006.js>`_
+
+.. js:autofunction:: p0006
+
+.. literalinclude:: ../../javascript/p0006.js
+   :language: javascript
+   :linenos:

docs/javascript/p0008.rst

@@ -0,0 +1,10 @@
+JavaScript Implementation of Problem 8
+======================================
+
+View source code `here on GitHub! <https://github.com/LivInTheLookingGlass/Euler/blob/master/javascript/p0008.js>`_
+
+.. js:autofunction:: p0008
+
+.. literalinclude:: ../../javascript/p0008.js
+   :language: javascript
+   :linenos:

docs/javascript/p0009.rst

@@ -0,0 +1,10 @@
+JavaScript Implementation of Problem 9
+======================================
+
+View source code `here on GitHub! <https://github.com/LivInTheLookingGlass/Euler/blob/master/javascript/p0009.js>`_
+
+.. js:autofunction:: p0009
+
+.. literalinclude:: ../../javascript/p0009.js
+   :language: javascript
+   :linenos:

javascript/p0006.js

@@ -0,0 +1,32 @@
+/**
+ * Project Euler Problem 6
+ *
+ * This turned out to be really easy
+ *
+ * Problem:
+ *
+ * The sum of the squares of the first ten natural numbers is,
+ * 1**2 + 2**2 + ... + 10**2 = 385
+ *
+ * The square of the sum of the first ten natural numbers is,
+ * (1 + 2 + ... + 10)**2 = 55**2 = 3025
+ *
+ * Hence the difference between the sum of the squares of the first ten natural
+ * numbers and the square of the sum is 3025 − 385 = 2640.
+ *
+ * Find the difference between the sum of the squares of the first one hundred
+ * natural numbers and the square of the sum.
+ *
+ * @return {number}
+ */
+
+exports.p0006 = function() {
+    let sum = 1;
+    let sum_of_squares = 1;
+    for (let i = 2; i < 101; i++) {
+        sum_of_squares += i * i;
+        sum += i;
+    }
+    let square_of_sum = sum * sum;
+    return square_of_sum - sum_of_squares;
+}

javascript/p0008.js

@@ -0,0 +1,73 @@
+/**
+ * Project Euler Problem 8
+ *
+ * In Python I did this with an iterator, but that is more cumbersome here,
+ * so I just did it with a loop that slices and takes advantage of JavaScript's type coersion
+ *
+ * Problem:
+ *
+ * The four adjacent digits in the 1000-digit number that have the greatest
+ * product are 9 × 9 × 8 × 9 = 5832.
+ *
+ * 73167176531330624919225119674426574742355349194934
+ * 96983520312774506326239578318016984801869478851843
+ * 85861560789112949495459501737958331952853208805511
+ * 12540698747158523863050715693290963295227443043557
+ * 66896648950445244523161731856403098711121722383113
+ * 62229893423380308135336276614282806444486645238749
+ * 30358907296290491560440772390713810515859307960866
+ * 70172427121883998797908792274921901699720888093776
+ * 65727333001053367881220235421809751254540594752243
+ * 52584907711670556013604839586446706324415722155397
+ * 53697817977846174064955149290862569321978468622482
+ * 83972241375657056057490261407972968652414535100474
+ * 82166370484403199890008895243450658541227588666881
+ * 16427171479924442928230863465674813919123162824586
+ * 17866458359124566529476545682848912883142607690042
+ * 24219022671055626321111109370544217506941658960408
+ * 07198403850962455444362981230987879927244284909188
+ * 84580156166097919133875499200524063689912560717606
+ * 05886116467109405077541002256983155200055935729725
+ * 71636269561882670428252483600823257530420752963450
+ *
+ * Find the thirteen adjacent digits in the 1000-digit number that have the
+ * greatest product. What is the value of this product?
+ *
+ * @return {number}
+ */
+
+exports.p0008 = function() {
+    let string = (
+        "73167176531330624919225119674426574742355349194934" +
+        "96983520312774506326239578318016984801869478851843" +
+        "85861560789112949495459501737958331952853208805511" +
+        "12540698747158523863050715693290963295227443043557" +
+        "66896648950445244523161731856403098711121722383113" +
+        "62229893423380308135336276614282806444486645238749" +
+        "30358907296290491560440772390713810515859307960866" +
+        "70172427121883998797908792274921901699720888093776" +
+        "65727333001053367881220235421809751254540594752243" +
+        "52584907711670556013604839586446706324415722155397" +
+        "53697817977846174064955149290862569321978468622482" +
+        "83972241375657056057490261407972968652414535100474" +
+        "82166370484403199890008895243450658541227588666881" +
+        "16427171479924442928230863465674813919123162824586" +
+        "17866458359124566529476545682848912883142607690042" +
+        "24219022671055626321111109370544217506941658960408" +
+        "07198403850962455444362981230987879927244284909188" +
+        "84580156166097919133875499200524063689912560717606" +
+        "05886116467109405077541002256983155200055935729725" +
+        "71636269561882670428252483600823257530420752963450"
+    );
+    let answer = 0;
+    for (let i = 0; i < string.length - 13; i++) {
+        let prod = 1;
+        for (let c = i; c < i + 13; c++) {
+            prod *= string[c];
+        }
+        if (prod > answer) {
+            answer = prod;
+        }
+    }
+    return answer;
+}

javascript/p0009.js

@@ -0,0 +1,34 @@
+/**
+ * Project Euler Problem 9
+ *
+ * Brute force on this problem has been very effective, so why stop now
+ *
+ * Problem:
+ *
+ * A Pythagorean triplet is a set of three natural numbers, a < b < c, for which,
+ * a**2 + b**2 = c**2
+ *
+ * For example, 3**2 + 4**2 = 9 + 16 = 25 = 5**2.
+ *
+ * There exists exactly one Pythagorean triplet for which a + b + c = 1000.
+ * Find the product abc.
+ *
+ * @return {number}
+ */
+const MAX = 500;
+
+exports.p0009 = function() {
+    for (let c = 3; c < MAX; c++) {
+        let c_square = c * c;
+        for (let b = 2; b < c; b++) {
+            let b_square = b * b;
+            for (let a = 1; a < b; a++) {
+                let a_square = a * a;
+                if (a_square + b_square == c_square && a + b + c === 1000) {
+                    return a * b * c;
+                }
+            }
+        }
+    }
+    return 0;
+}

javascript/test.js

@@ -4,6 +4,9 @@ const assert = require('assert');
 const answers = {
     1: 233168,
     2: 4613732,
+    6: 25164150,
+    8: 23514624000,
+    9: 31875000,
 };
 const knownSlow = [];
 let benchmarkReport = '';